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526 Cards in this Set
- Front
- Back
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Which species of wood is considered to be the standard when comparing other woods for use in aircraft structure? |
Sitka spruce.
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Why must abrupt changes in the cross-sectional area of a wooden structural member be avoided?
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Abrupt changes in the cross sectional area of a structural member concentrate stresses and can cause failure.
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What is the basic difference between laminated wood and plywood?
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In laminated wood all of the grain runs in the same direction, in plywood the grain in the layers cross the others at 90° or 45° angle. |
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What effect does moisture have on a wood aircraft structure?
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Moisture causes the wood to swell and crack as it dries out. It allows fungus to develop in the wood and cause it to decay. |
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Can northern white pine be used as a substitute for spruce?
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Yes, but it must be increased in size to compensate for its lower strength.
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Which wood is more inclined to warp, flat grain or vertical grain?
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Flat grain.
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How do you detect decay in a wood structure?
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Stick a sharp-pointed knife blade in the suspect area and pry the wood up. If the wood is good, it will come up as a long splinter; if it is decayed it will come up as a chunk.
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Are mineral streaks in a piece of structural aircraft wood reason for rejecting the wood?
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No, if there is no evidence of decay in the wood.
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How is compression wood identified?
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It has a high specific gravity, it appears to have the excessive growth of summerwood, and little contrast between springwood and summerwood.
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Is a hard knot, 1/2-inch in diameter allowed if it is in the web of a wing spar?
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No, 3/8-inch diameter is the maximum allowable knot, and it must meet severe restrictions.
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Are pin knot clusters allowable in aircraft structural wood?
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Yes, if they cause only small effect on grain direction.
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What kind of glue is recommended for making repairs to a wood aircraft structure?
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Synthetic resin or resorcinol glue.
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What reference material may be used for acceptable repairs to wood aircraft structure?
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AC 43.13-1B, Chapter 1.
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How is a scarf splice on a wing spar reinforced?
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Solid spruce or birch plywood reinforcing plates are glued to each side of the spar, centered at each end of the scarf.
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What is the correct repair to a wooden aircraft wing spar if the wing-attach bolt holes in the spar are elongated?
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Splice in a new section of the spar and drill new holes.
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What is the minimum taper to use when repairing a wood wing rib cap strip?
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12 times the thickness recommended, 10 times is minimum.
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How is aircraft plywood prepared for making a compound bend?
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Soak the wood in hot water until it is pliable.
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What is used to apply pressure to a glued joint when splicing a wood aircraft wing spar?
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Cabinetmakers' parallel clamps.
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How much pressure must be applied to glue joint in the piece of softwood to produce a strong joint? |
125 to 150 pounds per square inch. |
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What kind of repair is recommended for a hole in the plywood skin of an aircraft wing?
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A scarf patch.
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What is the recommended taper for a splayed patch in a plywood aircraft skin?
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5 to 1.
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What is the recommended taper for a scarf patch in a plywood aircraft skin?
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12 to 1.
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Why should sandpaper never be used when preparing a scarf joint in a wing spar for splicing?
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The dust caused by sanding will plug the pores of the wood so the glue cannot get in to for a good bond.
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What is the largest hole in a plywood wing skin that can be repaired with a fabric patch?
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1-inch in diameter.
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Why are light steel bushings often used in bolt holes in a wood wing spar?
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The bushing keeps the spar from being crushed when the nut on the attachment bolt is tightened.
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How long should a glue joint be kept under pressure when splicing a wood aircraft wing spar?
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For at least 7 hours.
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Which area of wood wing spar must not maintain any splice?
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There must be no splice under wing attach fittings, landing gear fittings, engine mount fittings, or lift and interplane strut fittings.
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What is done to a splice in a wood aircraft wing spar to strengthen the splice?
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Reinforcing plates are glued to both sides of the splice.
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What reference material may be used for acceptable covering methods for fabric-covered aircraft structure?
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AC 43.13-1B, Chapter 2.
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What are three types of fabric that can be used to cover an aircraft?
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Cotton fabric, polyester fabric, and glass fabric.
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What paperwork must be completed if an aircraft that was originally covered with Grade-A cotton fabric is re-covered using a synthetic fabric?
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The covering must be done according to a Supplemental Type Certificate, and a Form 337 must be executed, stating that all materials and processes complied with the requirements of the STC.
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What type of rib lacing cord is recommended or attaching cotton fabric to an aircraft structure?
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Waxed linen cord.
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What is meant by the selvage edge of a piece of fabric?
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It is the woven edge of fabric used to prevent the material unraveling during normal handling.
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Why are some portions of the structure of an aircraft dope proofed before they are covered with fabric?
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Dope proofing keeps the fabric from sticking to the structure when the first coat of dope is applied. The fabric normally sags enough to touch the structure before it begins to pull taut.
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What material is used for inter-rib bracing in a fabric-covered aircraft wing?
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Cotton reinforcing tape.
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What is the preferred seam used for machine-sewing pieces of aircraft fabric together?
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The French fell seam.
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Should a sewed seam in the fabric used to cover an aircraft wing run spanwise or chordwise?
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Both spanwise and chordwise seams are permissible, but chordwise seams are preferred.
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What are two methods of applying the fabric to the wing of an airplane?
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The blanket method and the envelope method.
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What material is used to cover the overlapping edges of the leading edge metal to protect the fabric?
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Cloth tape.
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What are two methods of attaching the fabric to the aircraft structure?
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By sewing and with a cement.
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How are the wrinkles pull out of cotton fabric?
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Wet the cotton with water and allow it to dry.
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How is polyester fabric shrunk on the aircraft structure?
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With heat from an iron.
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What type of knot is used for locking the stitches that are used for rib lacing on a fabric-covered aircraft wing?
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A modified seine knot.
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What determines the spacing of the rib lacing stitches on a fabric-covered aircraft wing?
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The never-exceed speed of the aircraft.
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When is the finishing tape applied to a fabric-covered wing when it is being recovered?
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After the second coat of dope has dried and the nap of the fabric has been sanded off.
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What is an antitear strip, and when are they required on a fabric-covered aircraft?
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An antitear strip is a strip of the same type of fabric as is used for covering the wings. It is laid over the rib between the reinforcing tape and the fabric. An antitear strip is required for aircraft that have a never-exceed speed in excess of 250 miles per hour.
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When are drainage grommets applied when an aircraft is being re-covered?
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They are laid into the third coat of dope, at the same time the surface tape is applied.
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Where are drainage grommets located on a fabric-covered aircraft wing?
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At the lowest point in each bay. It is customary to install a grommet on each side of a wing rib, on the underside of the wing, at the trailing edge.
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What is done to cotton and linen fabric to protect it from mildew?
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The first coat of dope used on cotton and linen fabric has a mildewcide mixed in it.
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How wide should the surface tape be that is used to cover the trailing edge of an aircraft wing?
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Three inches wide.
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Why is the surface tape used on the trailing edge of control surfaces of some airplanes notched?
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Since the edges of this tape face into the wind, it is possible that it could start to lift and form a very effective spoiler. If the tape is notched, it will tear off at a notch.
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What is the purpose of the reinforcing tape used between the fabric and the rib lacing on an aircraft wing?
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The reinforcing tape keeps the rib lacing cord from pulling through the fabric.
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What is the minimum strength to which aircraft fabric is allowed to deteriorate before it is considered to be unairworthy?
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Fabric can deteriorate to 70% of the strength of the fabric required for the aircraft.
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How is the strength of the fabric on an aircraft structure determined?
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An approximate strength test can be made with an FAA-approved fabric punch tester, but the only way to know for sure that the fabric has sufficient strength is by pull-testing a one-inch-wide sample of the fabric.
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What is the recommended type of repair to a fabric-covered aircraft surface when it has an L-shaped tear, with each of the legs of the tear more than 14 inches long?
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If the never-exceed speed of the aircraft is less than 150 miles per hour, a doped-on repair can be made.
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What type of hand-sewing stitch is used when sewing in a panel of new fabric on an aircraft fabric-covered wing?
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A baseball stitch, locked every eight to ten stitches.
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Where are the registration marks required to be placed on a fixed-wing aircraft?
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On a vertical tail surface or on the side of the fuselage.
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What is generally required dimensions of the registration numbers on the side of a fixed-wing aircraft?
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12-inches tall and 2/3 as wide as they are high. The letters M and W may be as wide as they are high. The numeral 1 is 1/6 as wide as it is high.
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What is the regulation regarding the color of the registration marks?
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The color must contrast with the background and be legible.
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Why should wooden wing spars be finished with a transparent varnish?
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The transparent finish allows any decay or rot that develops in the wood to be detected.
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Why is retarder used in dope when the dope is being sprayed in humid conditions?
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The retarder slows the drying of the dope and keeps it from blushing.
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When an aircraft is being recovered, when is fungicidal dope applied to the fabric?
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With the first coat of dope that is brushed into the fabric.
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What will happen if dope is sprayed over an enameled surface?
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the thinner in the dope will penetrate the enamel surface and cause it to swell.
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What are the two basic types of dope used on fabric-covered aircraft?
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Nitrate dope and butyrate (cellulose and acetate butyrate, or CAB) dope.
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What kind of dope is used on polyester synthetic fabric that has been heat-shrunk on an aircraft structure?
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Nonautening butyrate dope.
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Why are some portions of the structure of an aircraft dope proofed before they are covered with fabric?
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Dope proofing keeps the fabric from sticking to the structure when the first coat of dope is applied. The fabric normally sags enough to touch the structure before it begins to pull taut.
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What is meant by dope blushing, and what causes it?
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Blushing is a condition in dope finished in which moisture from the atmosphere condenses on the surface and causes some of the cellulose to precipitate from the finish. Blushing leaves a porous, dull, and weak finish.
Blushing may be caused by the temperature being too low, the humidity being too high, or by drafts or sudden changes in the temperature. |
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What can be done to remedy blushing that has formed on a doped surface that has just been sprayed?
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Spray a very light mist coat of a mixture of one part retarder to two parts of thinner over the blushed area. Allow it to dry and spray on another coat. If this does not remove the blush, the blushed dope will have to be sanded off and new dope applied.
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What is a rejuvenator?
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A slow-drying finishing material that has potent solvents and plasticizers that soften a dried surface film and restore resilience to the film.
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Does rejuvenator restore strength to the fabric?
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No, it only restores resilience to the finish.
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Why is the first coat of dope brushed onto the fabric?
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To ensure thorough penetration and encapsulation of all the fibers.
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What is the general reason for runs and sags in a finish that is being sprayed onto a flat surface?
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Too much dope is being applied. The film is too thick.
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What is the most common cause for dope roping?
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The dope was improperly thinned or it was too cold.
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What causes pinholes in a dope finish?
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Excessive atomizing air pressure on the spray gun.
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Why should the first coat of dope be thinned?
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To ensure thorough penetration and encapsulation of all of the fibers.
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Why is aluminum pigmented dope used on a fabric-covered aircraft?
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To protect the clear dope and the fabric from the harmful effects of the sun.
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What safety precaution must be observed when sweeping a paint room that has dried dope or lacquer overspray on the floor?
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The floor must be wet down with water before it is swept. Static electricity from dry sweeping can cause a fire.
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Why should a fabric-covered surface be electrically grounded when dry-sanding it?
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Dry-sanding can create enough static electricity on the surface that it can cause a spark and ignite the dope fumes inside the structure.
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What instructions must be followed when covering and finishing an aircraft with materials specified in a Supplemental Type Certificate (STC)?
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The instructions that are a part of the STC.
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What finishing materials must be used when recovering an aircraft using an STC?
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The finishing materials specified by the STC.
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How thick should a coat of wash primer be that is used on an aluminum alloy structure?
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It should be thin enough that it does not hide the surface of the metal.
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When mixing epoxy paint, should the converter be added to the resin or the resin to the converter?
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The converter should always be added to the resin, never the resin to the converter.
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What are three types of primer that may be used when painting an aircraft?
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Zinc chromate primer, wash primer, and epoxy primer.
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What type of thinner is used with zinc chromate primer?
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Toluol or toluene.
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What type of primer is used when the maximum protection of the metal is required?
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Epoxy primer.
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What should be done to a corroded aluminum alloy surface after the corrosion has been removed by mechanical methods?
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The surface should be treated with a chemical conversion coating before the topcoats are applied.
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What may be done to the surface to prevent filiform corrosion beneath the topcoat?
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Be sure that the primer is properly and completely cured.
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How is the finish removed from a fiberglass aircraft component that is being repaired?
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The finish must be sanded off. Paint remover can soften the resin of which the component is made.
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How can a vinyl film decal be removed from an aluminum alloy surface?
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Place a cloth saturated with cyclohexanone or MEK over the decal until it is softened, and scrape it off of the surface with a plastic scraper.
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What is a cause of poor adhesion between the topcoat and the fill coats on a fabric surface?
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Too much aluminum powder in the aluminum pigmented dope.
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What is a cause of a rough finish on a freshly sprayed surface?
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Too high atomizing air pressure on the spray gun.
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What causes sags and runs on a surface that has just been sprayed?
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Too much finishing material being applied in one coat.
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What causes orange peel, or spray mottle, in a finish?
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Incorrect paint viscosity or improper setting of the spray gun.
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What causes pinholes in a finish?
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Excessive atomizing air on the spray gun.
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What causes blushing in a dope finish?
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Too high humidity.
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What causes fisheyes in the finish?
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Localized surface contamination.
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For maximum strength of a formed sheet metal fitting, should the bend be made along or across the grain of the metal?
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Across the grain.
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What determines the minimum bend radius that can be used when forming a sheet metal structural fitting?
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The alloy, the metal thickness, and its hardness.
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What is meant by the neutral axis in a sheet of metal?
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A plane within the metal that neither stretches nor shrinks when the metal is being bent.
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What is a mold line in the development of a flat pattern for a formed metal part?
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An extension of the flat sides beyond the radius.
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What is the bend tangent line?
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A line in a flat pattern layout at which the bend starts.
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What is meant by setback?
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The distance the jaws of a brake must be set back from the mold line to form a bend.
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What is meant by bend allowance?
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The actual amount of metal in a bend. It is the distance between the bend tangent lines in a flat pattern layout.
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What is a sight line?
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A line drawn on a flat pattern layout within the bend allowance that is one bend radius from the bend tangent line. When the sight line is directly below the nose of the radius bar on the brake, the bend will start at the bend tangent line.
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What type of device is a Cleco fastener?
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A patented fastener that is inserted in the rivit holes and used to hold the two pieces of sheet metal together until they can be riveted.
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What is the main function of throatless shears in an aircraft sheet metal shop?
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Throatless shears are used to cut mild carbon steel up to 10-gage, and stainless steel up to 12-gage. They can be used to cut irregular curves in the metal.
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What kind of metal forming is done by a slip roll former?
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Simple curves with a large radius.
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What kind of metal forming is done by bumping?
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Compound curves in sheet metal.
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When forming a curved angle, what must be done to the flanges?
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The flanges must be stretched for a convex curve and shrunk for a concave curve.
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When hand-forming a piece of sheet metal that has a concave curve, should the forming be started in the center of the curve, or at its edges?
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Start at the edges and work toward the center.
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What is meant by a joggle in a piece of sheet metal?
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A joggle is a small offset near the edge of a piece of sheet metal that allows the sheet to overlap another piece of metal.
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What is the minimum edge distance allowed when installing rivets in a piece of aircraft sheet metal structure?
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Two times the diameter of the rivet shank.
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What is the recommended transverse pitch to use when making a riveted two row splice in a piece of sheet metal?
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Three-fourths of the distance between the rivets in the rows.
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Why should aluminum alloy rivets be driven with as few blows as is practical?
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Excessive hammering will work-harden the rivets and make them difficult to drive.
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What determines whether a piece of sheet metal should be dimpled or countersunk when installing flush rivets?
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The thickness of the sheet. Countersinking should be done only when the thickness of the sheet is greater than the thickness of the rivet head.
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What type of metal should be hot-dimpled?
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7075-T6, 2024-T81 aluminum alloys, and magnesium alloys should be hot-dimpled.
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What should be done to protect a riveted joint between aluminum alloy and magnesium alloy from corrosion?
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Coat the faying surface with a corrosion-inhibiting primer, dip the rivets in the primer and drive them while the primer is wet.
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Which stringer attached to a wing skin would require the greatest number of rivets for a splice?
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A stringer in the lower surface.
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What type of rivet may be used to replace a round head rivet in the aircraft structure?
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A universal head rivet.
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How long should a rivet be to join two pieces of sheet metal?
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The combined thickness of the metal sheets plus 1-1/2 times the rivet shank diameter.
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Should a riveted joint fail in shear or in bearing?
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It should fail in shear. The rivets should shear before the sheet tears at the rivet holes.
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What is the purpose of the beehive spring on a rivet gun?
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It holds the rivet set in the gun and allows the gun to vibrate the set.
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How can water entrapped in a honeycomb structure be detected?
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By the use of radiographic inspection.
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What effect can entrapped moisture have on metal honeycomb structure?
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Entrapped water can cause corrosion.
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What is the simplest way to detect delamination in a composite structure?
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Tap the surface with the edge of a coin. If the material is sound, the tapping will result in a clear ringing sound; but if it is delaminated, the sound will be a dull thud.
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What type of nondestructive inspection is suitable for detecting internal damage in honeycomb material?
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Ultrasonic inspection.
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What kind of repair can be made to a small damage of the core material and one face sheet of a piece of aluminum alloy honeycomb structure?
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A potted compound repair.
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What special precautions must be taken when repairing a radome?
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Nothing must be done to the radome that will affect its electrical transparency or its aerodynamic strength.
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How do you grind the point of a twist drill that is to be used for drilling transparent acrylic material?
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The cutting edge should be dubbed off to a zero rake angle, and the included angle of the tip should be ground to 140 degrees.
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What is a warp clock in a structural repair manual?
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An alignment indicator to show the orientation of the plies of a composite material. The ply direction is shown in relation to a reference direction.
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What are two advantages of laminated construction over riveted sheet metal?
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Light weight and rigidity.
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What are two popular types of core material used in laminated structure?
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Foam and honeycomb.
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What are two popular types of matrix material used in laminated structure?
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Polyester and epoxy resins.
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What are the two parts of a polyester matrix material?
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Resin and catalyst.
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What are the two parts of an epoxy matrix material?
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Resin and hardener.
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What are the two types of resins used in aircraft construction?
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Thermoplastic and thermosetting.
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What is necessary to cure a thermosetting resin?
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Heat.
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What are three materials that may be used to reinforce the matrix material for aircraft structure?
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Fiberglass, Kevlar®, and graphite.
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What is meant by unidirectional fabric?
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A fabric in which all of the major fibers run in the same direction.
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What is meant by the ribbon direction of a honeycomb material?
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The direction in a piece of honeycomb material that is parallel to the length of the strips of material that make up the core.
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What are two types of repair to a damaged honeycomb core composite material?
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Room-temperature cure repair and hot-bond repair.
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What is meant by the shelf life of a material?
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The normal length of time a material can be expected to keeps its usable characteristics if it is stored and not used.
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What is meant by the pot life of a resin?
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The length of time a resin will remain workable after the catalyst has been added.
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What document lists the safety hazards associated with a resin used in composite structure?
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The Material Safety Data Sheet for that resin.
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Of what class of resins are aircraft windows and windshields made?
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Thermoplastic.
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What type of transparent plastic material is used for most aircraft windshields?
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Acrylic plastic.
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How should sheets of transparent plastic material be stored?
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Leave the protective paper on the material and store it tilted approximately 10° from the vertical.
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How tight should the screws be tightened when installing an acrylic windshield in a channel?
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Tighten the screw to a firm fit and back it off one full turn.
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What is meant by crazing of transparent plastic material?
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Tiny hair-like cracks that may not extend all of the way to the surface. Crazing is caused by stresses or chemical fumes.
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What type of material is used to remove surface damage to a piece of acrylic resin?
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Micro-Mesh® abrasive sheets.
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What are the two fuel gases most generally used for gas welding?
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Oxygen and acetylene.
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What fuel gases are used for welding aluminum?
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Oxygen and hydrogen.
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What are two types of torches used in gas welding?
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Balanced-pressure torches and injector torches.
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What color lenses are used for gas welding steel?
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Green or brown.
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What color lenses are used for gas welding aluminum?
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Blue.
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Why is it important that the pressure of the gas in acetylene cylinder be kept low?
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Acetylene gas becomes unstable when it is kept under pressure of more than about 15 psi.
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What determines the amount of heat that is put into a weld by an oxy-acetylene torch?
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The size of the orfice in the torch tip.
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What is the difference in the appearance of an oxidizing flame, a neutral flame, and a reducing flame produced by an oxy-acetylene torch?
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An oxidizing flame has a pointed inner cone, and the torch makes a hissing noise. A neutral flame has a rounded inner cone, and there is no feather around the inner cone. A reducing flame has a definite feather around the inner cone.
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What is one method of minimizing distortion when making a long but weld?
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Skip welding minimized distortion. Tack weld the materials together and then complete the welds between the tacks, starting at a tack and working back toward the finished weld.
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What is meant by tack welding?
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Tack welding is the use of small welded spots to hold the material together until the final bead is run.
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Why must thick plates of metal be preheated before they are welded?
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Preheating is a method of controlling the expansion and contraction of the metal being welded. Preheating minimizes the stresses that are caused when welding thick metal.
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What must be done to an aircraft structure after it has been welded while clamped in a heavy jig or fixture?
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It must be normalized by heating it to a uniform red heat and allowed to cool slowly in still air.
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Why is it important that all traces of the welding flux be removed after a piece of aluminum or magnesium is welded?
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Welding flux is corrosive and it must be removed to keep the metal from corroding.
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What is the difference between brazing and welding?
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In brazing, the base metal is not melted, but is covered with a low-melting-point alloy. In welding, the base metal is melted.
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What kind of flame should be used when gas welding aluminum?
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A soft, neutral oxy-hydrogen flame.
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What is an acceptable acetylene line pressure to use when welding with an oxy-acetylene rig?
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About 5 psi.
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What kind of flame should be used when gas welding stainless steel?
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A slightly carburizing flame.
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How much should the bead penetrate the material when welding two pieces of steel with a butt weld?
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The joint should have 100% penetration.
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What is meant by a soft flame?
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A soft flame is one that is ade when the pressures of the gases are low enough that the flame does not make a noise and does not blow the puddle.
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What must be done to an aircraft fuel tank before it can be repaired by welding?
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The gasoline fumes must all be purged from the tank by running live steam through it for at least 30 minutes, by soaking it in hot water, or by filling it with nitrogen or carbon dioxide.
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What is another name for GTA welding?
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TIG welding.
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What type of shielding gases are used for GTA welding?
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Helium and argon.
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Why is GTA welding preferred over oxy-acetylene welding for building and repairing welded steel tube aircraft structure?
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The heat is concentrated in the weld and does not cause as much distortion as gas welding.
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What is the function of the inert gas used in GTA and GMA welding?
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The inert gas forms a shield to keep oxygen away from the weld puddle so oxides cannot form and weaken the weld.
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What is used as the electrode in GTA welding?
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A small-diameter tungsten wire.
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What are three types of power that can be used for GTA welding?
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DC-straight polarity, DC-reverse polarity, and AC.
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Which type of power provides the greatest heat and deepest penetration in GTA welding?
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DC-straight polarity.
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Which type of power is used for GTA welding aluminum and magnesium?
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DC-reverse polarity.
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What type of repair can be used when a steel structural tube is dented to more then 1/4 of its circumference?
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A patch may be welded over the damage.
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What type of repair can be used when a steel structural tube is dented at a cluster?
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A patch may be welded over the damaged area with fingers extending up along each member of the cluster.
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What is the preferred method of splicing a new piece of tubing into a structure?
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An inner sleeve splice.
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How is the inner sleeve tube held in the structural tube until the gap is welded?
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It is held in place with rosette welds.
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What is one limitation of using an outer-sleeve splice in an aircraft structure?
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This type of splice is not suitable where it would cause a bulge in the fabric.
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How should the ends of an outer-sleeve be cut?
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Cut it with a 30° fishmouth.
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What is the function of the flux used in soldering?
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Flux covers the cleaned and heated metal to keep oxygen away from it so oxides cannot form. Oxides keep the solder from adhering to the surface of the metal.
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What kind of solder is recommended for soldering electrical wires?
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60/40 resin-core solder.
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What is the composition of 60/40 solder?
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60% tin and 40% lead.
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What is the difference between soldering and brazing?
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Soldering is a method of joining metal parts with a molten nonferrous alloy that melts at a temperature below 800°F but lower than the melting temperature of the metal on which it is used.
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Why must acid-core solder never be used on electrical wire?
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The acid causes the wire to corrode.
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What determines the strength of a soldered joint?
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The mechanical connection of the joint, not the solder.
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What is the function of the ailerons on an airplane?
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Ailerons rotate the airplane about its longitudinal axis.
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What is a stabilator?
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A single-piece horizontal tail surface that acts as both the horizontal stabilizer and the elevators. A stabilator pivots about its front spar.
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What is the function of the elevators on an airplane?
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Elevators rotate the airplane about its lateral axis.
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What is the function of the rudder on an airplane?
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The rudder rotates the airplane about its vertical axis.
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What is the purpose of an aileron balance cable?
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It ties the ailerons together in such a way that when one aileron deflects downward the other one is pulled upward.
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What is an aerodynamically balanced control surface?
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A surface with part of its area ahead of the hinge line. When the surface is deflected, the portion ahead of the hinge aids the movement.
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What is meant by differential aileron travel?
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Aileron movement in which the upward-moving aileron deflects a greater distance than the one moving downward. The up aileron produces parasite drag to counteract the induced drag produced by the down aileron.
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What is a Frise aileron?
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An aileron with its hinge line set back from the leading edge so that when it is deflected upward, part of the leading edge projects below the wing and produces parasite drag to help overcome adverse yaw.
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What is a ruddervator?
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Movable control surfaces on a V-tail airplane that are controlled by both the rudder pedals and the control yoke. When the yoke is moved in or out, the ruddervators move together and act as the elevators. When the rudder pedals are depressed, the ruddervators move differentially and act as a rudder.
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How much is a fairlead allowed to deflect a control cable?
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No more than 3°.
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Why are the control cables of large airplanes normally equipped with automatic tension regulators?
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The large amount of aluminum in the aircraft structure contracts so much as its temperature drops in flight that the control cables could become dangerously loose. The automatic tension regulators keep the cable tension constant as the dimensions of the aircraft change.
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In what publications could you find correct control surface movement for a particular airplane?
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In the Type Certificate Data Sheet for the airplane.
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What causes dissymmetry of lift produced by the rotor of a helicopter?
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The forward speed of the helicopter produces dissymmetry of lift. The rotor blade that is traveling forward as the helicopter is flying produces more lift than the blade that is traveling rearward.
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Why do single-rotor helicopters use an auxiliary rotor on their tail?
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The thrust from the tail rotor counteracts the torque produced by the main rotor.
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Why is it important that the blades of a helicopter rotor system be in track?
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If the blades are not in track, vertical vibration can develop.
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What is the function of the collective pitch control of a helicopter?
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It changes the pitch of all the blades at the same time. The collective pitch controls the vertical flight of the helicopter.
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What is the function of the cyclic pitch control?
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It changes the pitch of the rotor blades at a particular point on their rotation to tilt the plane of the rotor. The cyclic pitch controls the lateral movement of the helicopter.
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What is the function of the tail rotor on a single main rotor helicopter?
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The thrust from the tail rotor counteracts the torque of the main rotor to control the yaw of the helicopter. The control pedals change the pitch of the tail rotor blades to vary the thrust.
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What is the purpose of the stabilizer system in a helicopter?
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A helicopter is statically stable but dynamically unstable. The stabilizer system restores the helicopter to level flight when outside forces cause it to pitch or roll.
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What is meant by a fully articulated rotor system?
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It is a rotor system in which the individual blades are free to flap, drag, and feather.
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What is meant by a semirigid rotor system?
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A two-blade rotor system in which the blades can feather, but cannot flap nor drag. The rotor hub is mounted on the mast with a teetering hinge that allows the entire rotor to rock as a unit.
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What is meant by a rigid rotor system?
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A rotor system that has freedom of motion about its feather axis only. The flexibility of the blades is sufficient to provide the needed flapping and dragging.
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What is the basic cause of low-frequency lateral vibration?
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The main rotor blades being out of static balance.
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What is the basic cause of low-frequency vertical vibration?
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One of the main rotor blades producing more lift than the other.
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What is usually the cause of high frequency vibration?
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The engine, cooling fan, or tail rotor.
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What is the most effective way to check a helicopter rotor for dynamic balance?
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Use a special computerized analyzer/balancer.
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Why is it important that control surfaces be statically balanced?
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An out-of-balance control surface can cause severe flutter.
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Where can you find the specifications for balancing the control surfaces of an airplane?
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In the aircraft maintenance manual.
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What in addition to static unbalance can cause a control surface to flutter?
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Worn hinges or improperly adjusted control cable tension.
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Where can you find instructions for jacking one wheel of an aircraft to change a tire?
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In the aircraft maintenance manual.
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Where can you find instructions for jacking the complete aircraft to perform a landing gear retraction test?
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In the aircraft maintenance manual.
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Where can you find instructions for hoisting an aircraft to replace wheels with floats?
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In the aircraft maintenance manual.
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What must the mechanic give the owner or operator of an aircraft if the aircraft he is giving a 100-hour inspection to proves to be unairworthy?
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A signed and dated list of all the discrepancies that keep the aircraft from being airworthy.
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Where can you find the recommended statement to use for recording the approval or disapproval of an aircraft to return to service after a 100-hour inspection?
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In 14 CFR §43.11.
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Under what conditions can an aircraft be operated with a 100-hour inspection overdue?
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The aircraft can be operated for no more than 10 hours after an inspection is due for the purpose of flying it to a place where the inspection can be performed.
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For how long can an aircraft be operated if a 100-hour inspection is overdue?
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For no more than 10 hours. The time beyond the 100 hours must be subtracted from the time before the next inspection is due.
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Under what conditions can an aircraft that is due an annual inspection be operated?
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It can only be flown when a special flight permit is issued.
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What certification is required for a mechanic to be able to approve an aircraft for return to service after a 100-hour inspection?
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A mechanic certificate with Airframe and Powerplant ratings.
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What determines whether or not an aircraft must be given a 100-hour inspection?
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Aircraft that carry persons for hire and aircraft that are used for flight instruction for hire must be given 100-hour inspections.
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What is the difference between an annual inspection and a 100-hour inspection?
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The inspections themselves are identical. An annual inspection can be conducted only by an A&P mechanic who holds an Inspection Authorization, while a 100-hour inspection can be performed by an A&P mechanic without an IA.
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What certification is required for a mechanic to conduct an annual inspection and approve the aircraft for return to service after the inspection?
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A mechanic certificate with Airframe and Powerplant ratings and an Inspection Authorization.
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What is a progressive inspection?
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An inspection of the same level as an annual inspection but approved by the FAA to be performed on a schedule that does not require the aircraft to be out of service for the time necessary to perform the entire inspection all at once.
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Does the FAA require that a checklist be used when conducting an annual or a 100-hour inspection?
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Yes, according to 14 CFR §43.15(c)(1).
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What certification is required for a mechanic to conduct a progressive inspection?
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A mechanic certificate with an Airframe and Powerplant ratings and an Inspection Authorization.
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Where can you find the requirements for inspecting the altimeter and static systems of aircraft operated under Instrument Flight Rules?
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In 14 CFR part 43, Appendix E.
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Where can you find the requirements for inspecting the ATC transponder that is installed in an aircraft?
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In 14 CFR Part 43, Appendix F.
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What items must be inspected on a helicopter in accordance with the instructions for Continued Airworthiness?
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The drive shafts or similar systems, the main rotor transmission gear box, the main rotor and center section, the auxiliary rotor.
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Must all manufacturer's service letters, instructions, and bulletins be complied with on an annual or 100-hour inspection?
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Not unless they have been incorporated into an airworthiness directive.
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For how long must the record of a 100-hour inspection be retained in the aircraft maintenance records?
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For one year, or until the next 100-hour inspection is completed.
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For how long must the record of the current status of life-limited parts of an engine be retained?
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This is part of the permanent records and it must be retained and transferred with the aircraft when it is sold.
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Where may the instructions for greasing a retractable landing gear on an aircraft be found?
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In the aircraft maintenance manual.
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Where may a list of the approved lubricants for greasing the aircraft retractable landing gear be found?
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In the aircraft maintenance manual.
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Where can you find safety precautions for jacking an aircraft for retractable landing gear inspection and maintenance?
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In the aircraft maintenance manual.
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What is the purpose of the centering cam in a nose-wheel shock strut?
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The centering cam forces the nose wheel straight back with the strut before it is retracted into the nose-wheel well.
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How does a shimmy damper keep a nose wheel from shimmying?
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It acts as a small hydraulic shock absorber between the piston and the cylinder of the nose-wheel shock strut.
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Where can you find the specifications for the type of fluid used to service an aircraft landing gear shock strut?
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On the nameplate on the strut.
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What absorbs the initial landing impact in an oleo shock strut?
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The transfer from oil from one compartment to another through a metered orifice.
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What absorbs the taxi shocks on an oleo shock strut?
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The compressed air or nitrogen.
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How much oil should be put into an oleo shock strut?
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With the strut completely deflated, fill it to the level of the filler plug.
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How much air or nitrogen should be put into an oleo shock strut?
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With the strut serviced with fluid and other filler plug in place and the weight of the aircraft on the strut, put in enough air or nitrogen to extend the piston to the height specified in the aircraft maintenance manual.
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What is the purpose of using an exerciser jack when servicing a shock strut with fluid?
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The jack moves the piston up and down the inside the cylinder to work all of the air out of the oil to be sure that the proper amount of oil is in the strut.
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Where can you find a list of brake fluids approved for the aircraft?
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In the aircraft service manual.
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What is used to flush brake lines and cylinders if the system uses vegetable-base fluid?
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Alcohol.
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What is used to flush brake lines and cylinders if the system uses mineral-base fluid?
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Naphtha, varsol, or Stoddard solvent.
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How do you measure the amount of brake lining wear on single disk brakes?
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Measure the clearance between the disk and the inboard side of the brake housing with the brakes applied.
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What is the purpose of the debooster in the hydraulic power brake system?
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The debooster decreases the pressure and increases the volume of fluid going to the brakes. This gives the pilot better control of the brakes.
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What should be done to hydraulic brakes when the pedal has a spongy feel?
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The spongy feel is caused by air in the brake. The brakes should be bled of this air.
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What is the purpose of the compensator port in the master cylinder of aircraft brakes?
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The compensator port in the master cylinder opens the brake reservoir to the wheel cylinders when the brakes are off. This prevents pressure from building up in the brake lines and causing the brakes to drag.
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What is the purpose of the shuttle valve in the brake system of an aircraft using hydraulic power brakes?
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The shuttle valve is an automatic transfer valve. It allows the brakes to be operated by hydraulic system pressure under all normal conditions; but if this pressure is lost, it allows the brakes to be operated by the emergency backup system.
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How does an antiskid brake system keep the wheels of an aircraft from skidding on a wet runway?
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The antiskid system monitors the rate of deceleration of the wheels. If any wheel slows down faster than it should (as it would at the beginning of a skid), the pressure on the brake in that wheel is released until the wheel stops decelerating, then the pressure is reapplied.
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When removing a wheel from an aircraft to change the tire, when should the tire be deflated?
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After the aircraft is on the jacks, but before the axle nut is loosened.
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What should be used to deflate high-pressure tires?
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A deflator cap screwed onto the tire valve, the allow the air to escape through the hole in the side of the cap and not in the face of the mechanic.
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What is used in a split wheel to keep air from leaking between the two wheel halves?
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An O-ring seal.
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Where are cracks most likely to form in an aircraft wheel?
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In the bead seat area.
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What type of inspection should be used to inspect the beat seat area of a wheel for cracks?
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Eddy current inspection.
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What is meant by the ply rating of a tire?
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The number of plies of cotton fabric needed to produce the same strength as the actual plies in the tire.
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What is the function of the bead in a tire?
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The bead is made of high-strength carbon steel wire bundles and used to provide the strength and stiffness where the tire mounts on the wheel.
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Is it proper to use a tube in a tubeless tire?
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No, the inner liner of a tubeless tire is rough and it can chafe the tube in normal operation.
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What is the function of the grooves cut into the tread of a tire?
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The grooves produce the optimum traction with the runway surface.
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What is the most widely used read pattern for modern airplane tires?
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A series of straight grooves around the periphery of the tire.
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How should new aircraft tires be stored?
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In a dark, cool location away from electrical motors or battery chargers.
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Is it best to stores new tires vertically or horizontally?
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Vertically.
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What is is the most important maintenance procedure for aircraft tires?
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Keep them properly inflated.
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What should be used to remove oil from a tire?
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Mild soap and warm water.
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Where do you find the proper inflation pressure for an aircraft tire?
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In the aircraft service manual.
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Why should aircraft tire pressure be rechecked after it has been installed for about 24 hours with no load applied?
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The tire will stretch and the pressure will drop. The proper pressure must be restored.
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What causes an aircraft tire to wear more on the shoulders than in the center of the tread?
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Operating the tire in an underinflated condition.
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What causes an aircraft tire to wear more in the center of the tread than on the shoulders?
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Operating the tire in an overinflated condition.
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What should be done to an aircraft tire if the sidewalls are weather-checked enough to expose the cord?
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The tire should be scrapped.
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Where can you find the correct inflation pressure for the tires on an aircraft?
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In the aircraft service manual.
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What kind of filter is a micronic filter?
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A filter with a special paper element.
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What is a double-action pump?
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A pump that delivers fluid with the movement of the pump handle in both directions.
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Why do most engine-driven hydraulic pumps have a shear section in their drive couplings?
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If the pump should seize, the shear section will break, disconnecting the pump from the engine and preventing further damage.
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What does an unloading valve do in a hydraulic system?
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The accumulator holds pressure on the hydraulic fluid in the system. The pressure is held by compressed air or nitrogen acting on the fluid through a bladder, a diaphragm, or a piston.
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What is the purpose of an orifice check valve in an aircraft hydraulic system?
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An orifice check valve allows full flow of fluid in one direction through the valve, but restricts the flow in the opposite direction.
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Where are line-disconnect fittings normally located in an aircraft hydraulic system?
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Normally in the lines that connect the engine-driven pump to the aircraft hydraulic system.
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What is a single-action hydraulic actuating cylinder?
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A linear actuating cylinder that uses hydraulic fluid under pressure to move the piston in only one direction. The piston is returned by a spring.
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What is a sintered metal hydraulic filter?
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A surface filter whose element is made of powdered metal fused under heat and pressure.
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What is the purpose of the differential pressure indicator on a hydraulic filter?
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It indicates when the filter is clogged and fluid is bypassing the filter element.
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What is a Cuno filter?
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An edge filter made of a stack of thin metal disks separated by thin scraper blades. Contaminants collect on the edge of the disks and are periodically scraped out by rotating the disks. The contaminants collect in the bottom of the filter case for the future removal.
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Is a chevron seal a one-way or two-way seal?
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A one-way seal.
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To which side of a chevron seal should the pressure be applied?
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To the open side.
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Is an O-ring seal a one-way or a two-way seal?
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A two-way seal.
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How can you be sure of getting an O-ring made of the correct material for a specific hydraulic component?
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The O-ring must have the correct part number and it must have been obtained from a reputable source.
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On which side of an O-ring should the backup ring be placed?
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On the side away from the source of pressure.
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What should be done to the sharp edges of threads and actuator pistons when installing O-rings?
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The sharp edges should be covered with paper.
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What are two basic differences between a hydraulic and pneumatic system?
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The fluid in a pneumatic system is compressible and that used in a hydraulic system is incompressible. A pneumatic system has no return system.
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What are two functions of a low-pressure pneumatic system in an aircraft?
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To operate the gyros in flight instruments, and to inflate pneumatic deicer boots.
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What type of pump is used in a low-pressure pneumatic system?
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A vane-type pump.
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Why do high-altitude aircraft that have pneumatic gyro instruments use pressure-actuated instruments rather than vacuum-actuated instruments?
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At high altitude there is not enough air mass to drive the gyros at their required speed.
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What effect would a dirty inline air filter have on the operation of pneumatic gyro instruments?
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The instruments would not get enough air to spin up to their required speed.
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Of what material are the vanes in a dry type air pump made?
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Carbon.
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What kind of device is used to control the speed of movement of the piston in a pneumatic actuator?
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A variable orifice.
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What is the purpose of the moisture separator in a high-pressure pneumatic system?
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The separator collects moisture form the air and holds it on a baffle until the system is shut down. When the inlet pressure to the moisture separator drops below 450 psi, a drain valve opens and all of the accumulated moisture is discharged overboard. A moisture separator removes about 98% of the moisture in the air.
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What are two types of filters that are used in an aircraft pneumatic system?
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Micronic (paper) type, and screen type.
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What are the two basic types of hydraulic fluid used in modern aircraft?
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Mineral base fluid and phosphate ester base fluid.
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Does the main hydraulic pump take its fluid from the bottom of the reservoir, or from a standpipe?
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The main pump normally takes its fluid from a standpipe, while the emergency pump takes its fluid from the bottom of the reservoir. If a break in the system should allow the main pump to pump all of its fluid overboard, there will still be enough fluid in the reservoir to allow the emergency system to extend the landing gear and actuate the brakes.
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Why are some hydraulic reservoirs pressurized?
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Pressurization ensures that fluid will be supplied to the inlet of the pumps at high altitude where there is not enough atmospheric pressure to do this.
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What are two ways aircraft hydraulic reservoirs may be pressurized?
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By an aspirator in the fluid return line or by bleed air from one of the engine compressors.
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What is used to flush a hydraulic system that uses Skydrol hydraulic fluid?
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Trichlorethylene or the solvent recommended by the aircraft manufacturer.
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What is used to flush a hydraulic system that uses mineral base hydraulic fluid?
|
Naphtha, varsol or Stoddard solvent.
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Where can you find the type of hydraulic fluid required for a particular aircraft?
|
In the maintenance manual for the aircraft. This information is also on a placard on the system reservoir.
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What is used to remove phosphate-ester base hydraulic fluid from aircraft tires?
|
Soap and water.
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How can you be sure that a replacement seal in a hydraulic component is compatible with the fluid used in the system?
|
Use only the seal identified by part number that is specified in the component maintenance manual.
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What must be done to the lines that are disconnected when replacing an aircraft hydraulic system component?
|
They must be capped with the correct fluid line cap or plug. Masking tape or other types of adhesive tape should never be used.
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What must be done before a pressurized reservoir is serviced?
|
All of the pressure must be bled off.
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Where does the warm air come from that is used to heat the cabin of most small single-engine reciprocating-engine-powered aircraft?
|
From a shroud around the engine muffler.
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What is the danger of a leak in an exhaust system cabin heater?
|
Exhaust gases contain carbon monoxide (CO), a colorless, odorless, gas that can cause incapacitation or death to the aircraft occupants.
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How can an exhaust system be checked for leaks?
|
Pressurize it with the discharge from a vacuum cleaner and wipe the outside of the system with a soap solution. Any leak will cause bubbles to form.
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How can you tell that there is carbon monoxide in the aircraft cabin?
|
Indicator crystals in a CO detector will change color, from a normally bright color to a dark color. At lethal levels of CO they will turn black.
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Where does the fuel used in an aircraft combustion heater come from?
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From aircraft fuel tanks.
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What happens to a combustion heater if the flow of ventilating air is restricted?
|
If the ventilating air is restricted and the temperature reaches a preset value, the limit switch will cause the fuel to be shut off to the heater.
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What regulates the temperature in an aircraft cabin that is heated with a combustion heater?
|
A thermostat senses the cabin temperature and cycles the fuel valve on or off to maintain the temperature at the desired value.
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What maintenance is required for a combustion heater?
|
Clean the fuel filters and check for fuel leaks.
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What are two types of air conditioning systems that may be installed on an aircraft?
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Air-cycle systems and vapor-cycle systems.
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How is the heat removed from an aircraft cabin with a vapor-cycle air conditioning system?
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The cabin heat is absorbed by the refrigerant in the evaporator, then carried outside the aircraft where it is given up to the outside air in the condenser.
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What produces the cool air in a vapor-cycle air conditioning system?
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Warm cabin air is blown across the evaporator, where its heat is transferred into the refrigerant. The air that leaves the evaporator is cool.
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What is used as the refrigerant in a vapor-cycle air conditioning system?
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A Freon-type liquid refrigerant known as Refrigerant 12, or the more environmentally friendly R-134a.
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What is the state of the refrigerant as it leaves the compressor?
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It is a high-pressure gas.
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What is the state of the refrigerant as it leaves the condenser?
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It is a high-pressure liquid.
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What is the state of the refrigerant as it leaves the thermostatic expansion valve?
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It is a low-pressure liquid.
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What is the state of the refrigerant as it leaves the evaporator?
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It is a low-pressure vapor.
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How is the compressor lubricated?
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Refrigeration oil is mixed with the refrigerant and it circulates through the compressor and the entire system.
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What is the function of the thermostatic expansion valve?
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It meters just enough liquid refrigerant into the evaporator that all of it will be evaporated by the time it leaves the evaporator coils.
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How is refrigerant put into the system?
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It is put into the system through service valves on the low side of the system using a manifold gage set.
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How should the components in the low side of a properly operating vapor-cycle cooling system feel?
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They should feel cool.
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How is a vapor-cycle cooling system checked for refrigerant leaks?
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Hold the probe of an electronic leak detector below any suspect fitting or component. If there is a leak, the tone of the sound produced by the detector will change.
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What safety equipment should be worn when charging a vapor-cycle cooling system?
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A safety face shield that protects the entire face.
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Where does the warm air come from that is used to heat the cabin of a large jet transport aircraft?
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Warm engine compressor bleed air is used.
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Where is the first place the hot compressor bleed air gives up some of its heat in an air-cycle cooling system?
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In the primary heat exchanger.
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What is the function of the air-cycle machine in an air-cycle cooling system?
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The centrifugal compressor increases the pressure and temperature of the bleed air. This high temperature air gives up some of its heat in the secondary heat exchanger, and a great deal more as it drives the expansion turbine. It leaves the expansion turbine as cold air.
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Why must air-cycle air conditioning systems incorporate a water separator?
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The rapid cooling of the air in the expansion turbine causes moisture to condense in the form of fog. This moisture is trapped in the moisture separator before the air is released into the cabin.
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How is the temperature of the air produced by an air-cycle cooling system controlled?
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By a temperature control valve which mixes hot engine compressor bleed air with cold air from the expansion turbine.
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Why are the cabins of most turbine-powered aircraft pressurized?
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These aircraft fly at such high altitudes that supplemental oxygen would be needed for the occupants if the cabins were not pressurized.
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Where does the pressurizing air come from on most turbine-powered aircraft?
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From air bled from one of the engine compressors.
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Where does the pressurizing air come from on most smaller reciprocating-engine-powered aircraft?
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From the engine turbocharger.
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What determines the amount of pressurization that an aircraft can use?
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The structural strength of the aircraft cabin.
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How is cabin pressure controlled in a pressurized aircraft?
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More pressure than is needed is pumped into the aircraft cabin, and the pressure controller modulates the outflow valve to maintain the correct pressure in the cabin.
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What is meant by the isobaric mode of cabin pressurization?
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The isobaric mode of cabin pressurization is the mode that keeps the cabin altitude constant as the aircraft changes its flight altitude.
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What is meant by the constant differential mode of cabin pressurization?
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After the pressure in the aircraft cabin reaches the maximum value allowed by structural considerations, the constant differential mode of operation holds the pressure inside the cabin a constant amount above the outside air pressure.
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What is the function of the cabin outflow valve on a pressurized aircraft?
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The cabin outflow valve, which is controlled by the pressure controller, maintains the correct amount of pressure inside the cabin.
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What is the function of the cabin pressure safety valve on a pressurized aircraft?
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The cabin pressure safety valve prevents cabin pressure from exceeding the maximum allowable differential pressure.
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Why must pressurized aircraft have a negative pressure relief valve?
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The structure of an aircraft cabin is not designed to tolerate the inside pressure being lower than the outside pressure.
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What keeps the cabin of a pressurized aircraft from being pressurized when the aircraft is on the ground?
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A squat switch on the landing gear holds the safety valve open when the aircraft is on the ground.
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What are the two main gases that make up our atmosphere?
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Nitrogen and oxygen.
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What is used to check an oxygen system for leaks?
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A special leak-detector liquid that is a form of non-oily soap.
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Why must fittings in an oxygen system not be tightened to stop a leak when there is pressure on the system?
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When the system is pressurized the tubing is expanded slightly; if the fitting is tightened when it is expanded, it will likely leak when the pressure is reduced.
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What are three ways supplemental oxygen can be carried in an aircraft?
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As a high-pressure gas, in its liquid form, and as a solid in the form of a chemical candle.
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What kind of gaseous oxygen must be used to service an aircraft oxygen system?
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Only aviators' breathing oxygen. Hospital oxygen and welding oxygen contain too much moisture to be used.
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What is a continuous-flow oxygen system?
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An oxygen system that continuously flows a metered amount of oxygen into the mask.
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What is a pressure-demand oxygen system?
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An oxygen system that flows oxygen to the mask only when the wearer of the mask inhales. Above a specified altitude, the regulator meters oxygen under pressure into the mask when the wearer inhales.
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What identification must be stamped on an oxygen bottle carried in an aircraft?
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The identification DOT 3AA or DOT 3HT, the date of manufacture, and the date of all of the hydrostatic tests.
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To what pressure, and how often should DOT 3AA oxygen cylinders be hydrostatically tested?
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They should be tested to 5/3 of their working pressure every three years.
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To what pressure, and how often should DOT 3HT oxygen cylinders be hydrostatically tested, and when should they be retired from service?
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They should be tested to 3,083 psi every three years and retired from service after 15 years or 4,380 pressurizations, whichever occurs first.
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What kind of lubricant can be used for installing fittings in an oxygen system component?
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Teflon tape or a special water-base lubricant.
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What is used to check for leaks after replacing a fitting in an oxygen system?
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A special leak-detector liquid that is a form of non-oily soap.
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What cleaning solutions can be used to clean parts used in an oxygen system?
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Anhydrous ethyl alcohol, isopropyl alcohol, or freon.
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What may be used to dry components in an oxygen system after they have been cleaned?
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Water-pumped dry nitrogen.
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What may be used to purge the lines in an oxygen system after it has been opened for servicing?
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Water-pumped Dry nitrogen.
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What must be done before any maintenance can be done on an oxygen system?
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The oxygen supply must be turned off at the bottle valve.
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What error is corrected when an aircraft compass is swung?
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Deviation error.
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What fluid is used in an aircraft magnetic compass?
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A special water-clear fluid similar to kerosine.
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What is the maximum amount of deviation error allowed when a magnetic compass is installed in an aircraft?
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10 degrees.
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Where on an airport is a compass rose located?
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At a location where there is little traffic and the area is free from magnetic interference caused by electrical power lines or buried pipes.
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What is done to a compass to correct for deviation error?
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The compensating magnets in the compass are adjusted to minimize the effect of outside magnetic fields.
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Where should the compass correction card be placed?
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In plain sight of the pilot, near the compass.
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What are the gyroscopic instruments that are connected to the low-pressure pneumatic system of an aircraft?
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Heading indicator, attitude indicator, and turn-and-slip indicator.
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What device is used with a wet-pump vacuum system to prevent oil from getting into the deicer boots?
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An oil separator.
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What are two types of filters used with a pressure system for gyros?
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A pump inlet filter and an inline filter.
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What type of filter is used with a vacuum system for gyros?
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A central air filter.
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What two types of pumps are used in the low-pressure pneumatic system?
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A dry-type and a wet-type air pump.
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What are the vanes of a wet-type air pump made of?
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Steel.
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What are the vanes of a dry-type air pump made of?
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Carbon.
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How are the vanes of a wet-type air pump lubricated?
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With engine oil directed into the pump through a small hole in the base of the pump.
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Why is it important to use the correct gasket when replacing a wet-type air pump?
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The gasket must have a hold through which the pump lubricating oil can flow.
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Why do dry-type air pumps not need to be lubricated?
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The special carbon material of which the vanes are made wears away in microscopic amounts to provide the needed lubrication.
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What must be done to the gyro pressure system if a dry-type air pump fails?
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All of the filters must be replaced to prevent any debris from the pump vanes getting into the gyro instruments.
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Who is authorized to perform the altimeter tests to determine the accuracy of the altimeter?
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The manufacturer of the aircraft on which the tests are conducted, or a certificated repair station properly equipped and authorized to perform the test.
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Where are the requirements for the altimeter system tests found?
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14 CFR Part 43, Appendix E.
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How often should an altimeter be checked if it is installed in an aircraft used in IFR flight?
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Every 24 calendar months.
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What are 6 tests that must be made when testing an altimeter?
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Scale error, hysteresis, after-effect, friction, case leak, and barometric scale error.
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How much difference is allowed between the altitude indication on the automatic pressure altitude reporting equipment and that on the altimeter?
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125 feet.
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To what altitude must altimeters be tested?
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To the highest altitude the aircraft will be flown on IFR flight.
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What record must be made of a test of an altimeter?
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The aircraft permanent maintenance record must show the date, the maximum altitude to which the altimeter was tested, and the name of the person approving the aircraft for return to service after the test.
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Do the tests described in the 14 CFR Part 43, Appendix E apply to the altimeters installed in all certificated aircraft?
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No, only those operated under instrument flight rules in controlled airspace.
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To what avionic equipment is the output from encoding altimeter connected?
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The ATC transponder.
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What is the allowable difference between the surveyed elevation of the airport and the indication on the altimeter when it is set to the local altimeter setting?
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75 feet.
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What instruments in an aircraft are connected to the static system?
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The airspeed indicator, vertical speed indicator, and altimeter.
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Who is authorized to conduct a static system tests specified in 14 CFR §91.411?
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A certificated mechanic holding an airframe rating.
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How much leakage is allowed in the static system of an unpressurized aircraft?
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With a pressure differential of 1 inch of mercury, the system must not show a loss indicated altitude of more than 100 feet in one minute.
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How much leakage is allowed in the static system of a pressurized aircraft?
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With a pressure differential equal to the maximum cabin differential pressure for which the aircraft is certificated, the system must not show a loss of indicated altitude of more than 2 percent of the equivalent altitude of the maximum cabin differential pressure or 100 feet, whichever is the greater, in one minute.
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What indication on the altimeter shows that the pressure inside the static system has been decreased by 1 inch of mercury?
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The altimeter will show an increase of approximately 1,000 feet.
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When should a static system leak check be performed?
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Any time the static system has been opened.
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What should be done to the static port that is no being used to conduct the leak test?
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It should be taped over in such a way that the tape can not be overlooked or forgotten when the test is completed.
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On what two frequencies does the Emergency Locator Transmitter operate?
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121.5 and 243.0 megahertz.
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Where is the ELT transmitter normally located on an aircraft?
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In the tail of the aircraft or as far aft as possible, so it will be least likely to be damaged in a crash.
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How often should ELT batteries be replaced or recharged?
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When the transmitter has been in use for more than 1 cumulative hour, or when 50% of their useful life or charge has expired.
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How can you know when an ELT battery must be replaced or recharged?
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By the date marked on the outside of the transmitter.
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How often must ELTs be inspected for proper installation, battery corrosion, operation of the controls and sensor, and the presence of the radiated signal?
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Every 12 calendar months.
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What causes an ELT to actuate?
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An inertia switch that detects an impact parallel to the longitudinal axis of the aircraft as would occur in a crash.
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How is an ELT tested to determine that it is working?
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Actuate the test switch and listen on 121.5 or 243.0 MHz. Make the test during the first five minutes of the hour and do not allow the ELT to operate for more than 3 sweeps. If the ELT is operated outside of this time frame, you should contact the control tower before conducting the test.
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What kind of conductor is used to connect a VHF or UHF antenna to the receiver or transmitter?
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Coaxial cable.
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What is a coaxial cable?
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A type of two-conductor electrical cable in which the center conductor is encased in insulation inside a braided shield that serves as the outer conductor. Coaxial cables are normally used for attaching radio receivers and transmitters to antennas.
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How can you determine the proper coaxial cable and connectors to use in an aircraft radio installation?
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Refer to the radio installation instructions for the correct part number for the cable and connectors.
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What precautions should be taken when installing coaxial cable between a radio transmitter and its antenna?
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The routing should be as direct as possible, there should be no sharp bends in the coax, and it should be kept away from heat that could soften the insulation.
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What is a BNC connector?
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A coaxial cable connector that is connected by inserting the guide pins on the male connector into slots in the female connector and twisting the connector one quarter turn.
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What is the preferred location for a VOR antenna on an airplane?
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On top of the aircraft, along the center line of the fuselage.
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Which component of the Instrument Landing System shares the antenna with the VOR?
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The ILS localizer.
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What is the preferred location for a DME antenna?
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Along the center line of the belly of the aircraft, as far from any other antenna as is practical.
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What kind of antenna is used for VHF communications?
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A vertically polarized whip antenna.
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What kind of antenna is used for the ATC transponder?
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A UHF stub antenna.
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What is the preferred location for the ATC transponder antenna?
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On the center line of the belly of the aircraft as far from any other antenna as is practical.
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What two types of antenna are used with most ADF receivers?
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A directional loop antenna and a nondirectional sense antenna.
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Why is it necessary to install a doubler on the inside of the aircraft skin when antenna is mounted on the skin?
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The doubler reinforces the skin so wind loads on the antenna will not cause the skin to flex and crack.
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What is the basic purpose of an autopilot?
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It frees the human pilot from continuously having to fly the aircraft, and flies with a high degree of precision. It also couples with various electronic navigational aids.
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What are the basic subsystems of an automatic flight control system?
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Command, error-sensing, correction, and follow-up.
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What type of device is normally used in the error-sensing subsystem?
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Gyros.
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What are three types of servos that are used in the correction subsystem?
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Hydraulic, pneumatic, and electric.
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What is the purpose of the follow-up subsystem in an autopilot?
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It stops the control movement when the surface has deflected the proper amount for the signal sent by the error sensor.
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Is a certificated airframe mechanic allowed to adjust a communications transmitter?
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No, this requires a license issued by the Federal Communications Commission.
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Which frequency band is used for most aircraft communications?
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The VHF band, between 30 and 300 megahertz.
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In which frequency band does the VOR equipment operate?
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In the VHF band, between 108.0 and 117.95 megahertz.
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In what frequency band does the DME equipment operate?
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In the UHF band, between 962 and 1,024 megahertz, and between 1,151 and 1,213 megahertz.
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Which frequency band is used for long-range communications from an aircraft?
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The high frequency band (2 to 25 megahertz).
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What is meant by a transceiver?
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It is a piece of radio communications equipment in which all of the circuits for the receiver and the transmitter are contained in one housing.
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What is used as the sensor in the fuel tank for an electronic-type fuel quantity indicating system?
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Tubular capacitors that extend across the fuel tank from top to bottom.
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What is the principle upon which the electronic-type fuel quantity indicating system operates?
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Tubular capacitors extending across the fuel tanks change their capacitance as the fuel level changes. The dielectric constant (k) of the fuel is approximately twice that of air.
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What is used as a sensor in the fuel tank for the older resistance-type fuel quantity indicating system?
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A variable resistor with an arm that is moved by a float riding on top of the fuel in the tank.
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What are two types of fuel cells used in modern aircraft?
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Integral fuel cells (cells that are a sealed-off portion of the structure), and bladder-type cells.
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Why are fuel tanks divided into compartments or have baffles installed in them?
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The compartments or baffles keep the fuel from surging back and forth as the aircraft changes its attitude in flight.
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What is the purpose of a drip gage in the fuel tank of a large aircraft?
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The drip gage allows a mechanic to check the fuel level in a tank from the bottom of the tank.
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What markings must appear near the filler opening of the fuel tanks on reciprocating-engine-powered aircraft, and on a turbine-powered aircraft?
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On a reciprocating engine powered-aircraft: the word "Avgas" and the minimum grade of fuel.
On a turbine engine powered aircraft: the words "Jet Fuel," the permissible fuel designations, the maximum permissible fueling supply pressure, and the maximum permissible defueling pressure. |
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Where can you find the correct part number for the fuel quantity sensor to be installed in an aircraft fuel tank?
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In the Illustrated Parts Catalog for the aircraft.
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When must the fuel quantity indicating system indicate "zero?"
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During level flight when the fuel in the tank is equal to the unusable fuel supply.
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Where are fuel system strainers located?
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One strainer is located in the outlet to the tank, and the main strainer is located in the fuel line between the outlet of the fuel tank and the inlet to the fuel metering device.
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Why do the fuel strainer used on some turbine-engine aircraft have a warning device that signals the flight crew when the strainer is beginning to clog up?
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Strainers clog because ice forms on the filter element. The flight crew can route the fuel through a fuel heater to melt the ice.
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What must be done after a fuel system strainer has been cleaned or replaced?
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The system must be tested for leaks by pressurizing the system with the boost pump, if one is used.
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Why is it important to drain all of the fuel sumps before the first flight of the day?
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Water can condense in the fuel tanks and it must be drained out before the aircraft is safe for flight.
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Is the procedure of draining the sumps with the aircraft in the ground attitude an assurance that all of the water is removed from the tanks?
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No, some aircraft required special procedures to remove all of the water. Refer to the Aircraft Flight Manual or Pilot's Operating Handbook.
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How does water appear in the fuel drained from the tank sumps?
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Water appears as a clear globule in the bottom of the container used to collect the fuel drained from the sumps.
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What color is grade 100-LL fuel?
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Blue.
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How can you detect jet fuel in the sample taken from the tank sump drains?
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Jet fuel is basically clear and it has an odor similar to kerosine.
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What must be done if the sump drains sample shows traces of jet fuel?
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The fuel system must be drained and flushed out with the proper grade of aviation gasoline.
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Why must an aircraft fuel valve have a detent in its operating mechanism?
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The detent gives the pilot a positive indication by feel when the selector valve is in the full ON and full OFF position.
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What must be done before a fuel selector valve can be removed from an aircraft?
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The tank to which the valve is connected must be drained and otherwise isolated.
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What must be done after a fuel valve is replaced?
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The fuel system must be checked for leaks.
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How is a fuel leak indicated on a reciprocating-engine-powered aircraft?
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The dye in the gasoline stains the area around the leak.
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Why must a switch be derated if it is used in a circuit that supplies incandescent lamps?
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The high-inrush current caused by the low resistance of the cold filaments required that the switches be derated.
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What is an SPDT switch?
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A single-pole, double-throw switch.
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Where could you find the part number of a switch in an aircraft electrical system?
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In the equipment table of bull of materials on the electrical circuit diagram for the aircraft.
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If no specific instructions are available, which way should the operating handle of an electrical switch move to turn a component on?
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Forward or upward.
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What is meant by a trip-free circuit breaker?
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A circuit breaker that cannot be closed while a fault exists, regardless of the position of the operating handle.
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What is meant by a slow-blow fuse?
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A fuse that will allow more current than its rating to flow for a short period of time, but will open the circuit if more than its rated current continues to flow.
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What is the function of a fuse or circuit breaker in an aircraft electrical circuit?
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It protects the wiring form an excess of current. It will open the circuit if enough current flows to heat the wire until the insulation begins to smoke.
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What are two principles upon which circuit breakers operate?
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Magnetic circuit breakers open a circuit when the current creates a strong enough magnetic field. Thermal circuit breakers open a circuit when the current causes enough heat.
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What circuit in an aircraft electrical system is not required to have a circuit protective device?
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The main circuit for starter motors, used during starting only.
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Is an automatic-reset circuit breaker approved or aircraft electrical circuits?
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No, a manual operation is needed to restore service after the circuit breaker has tripped.
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What two things must you take into consideration when selecting the wire size to use in an aircraft electrical system installation?
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The current carrying capability of the wire and the voltage drop caused by the current flowing through the wire.
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What is the maximum number of wires that should be connected to any single stud in a terminal strip?
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Four.
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How is a wire bundle protected from chafing where the bundle goes through a hole in a fuselage frame or bulkhead?
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The edges of the hole are covered with a flexible grommet, and the bundle is secured to the structure with a cushioned clamp.
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What kind of clamp is used to secure a wire bundle to the aircraft structure?
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A cushioned clamp.
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Why are solderless splices usually better than soldered splices in the wiring of an aircraft electrical system?
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Soldered joints are usually stiff, and vibration can harden the wire and cause it to break. Solderless splices are designed to keep the joint flexible so vibration cannot cause the wire to break.
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What is the main disadvantage of aluminum wire over copper wire for use in an aircraft electrical system?
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Aluminum wire is more brittle than copper. It is more subject to breakage when it is nicked or when it is subjected to vibration.
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What size aluminum wire would be proper to replace a piece of four-gage copper wire?
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Two-gage. When you substitute aluminum wire for copper wire, use a wire that is two gage numbers larger.
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What is the smallest size aluminum wire that is approved for use in aircraft electrical systems?
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Six-gage.
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What color insulator on a preinsulated solderless connector indicates that the connector is proper for a 10-gage wire?
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Yellow.
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What size generator must be used in an aircraft electrical system if the connected electrical load is 30 amps, and there is no way of monitoring the generator output?
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When monitoring is not practical, the total continuously connected electrical load must be no more than 80% of the rated generator output. This would require a generator with a rating of 37.5 amps. Practically, a 40-amp generator would be installed.
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What is meant by "flashing" the field of a generator?
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Restoring the residual magnetism to the frame of the generator. This is done by passing battery current through the field coils in the direction it normally flows when the generator is operating.
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What is meant by paralleling the generators in a multi-engine aircraft?
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Adjusting the voltage regulators so all the generators share the electrical load equally.
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What are three types of voltage regulators used with aircraft generators?
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Vibrator-type, carbon-pile type, and solid state-type.
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How does a vibrator-type voltage regulator maintain a constant voltage?
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When the voltage rises above the desired value, an electromagnetic relay opens and inserts a resistor in the generator field circuit, decreasing the field current and lowering the generator output voltage.
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What two components are normally housed with a vibrator voltage regulator in a single-unit generator control?
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A current limiter and a reverse-current cutout relay.
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What is a squat switch and where is it located?
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A landing gear safety switch that energizes a circuit to prevent the landing gear retraction handle from being moved to the RETRACT position when weight is on the landing gear. It is located in the torsion links of one of the main landing gears.
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What kind of device is normally used as a sensor to detect the condition of a retractable landing gear?
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A precision Microswitch.
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What type of system is used to indicate the position of the wing flaps?
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Usually a resistance-type remote indicating system such as the DC Selsyn system.
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What information is shown by the wing flap position indicator?
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The number of degrees the flaps are lowered.
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What would cause the warning horn to sound when the throttles are pulled back, reducing the engine power for landing?
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The warning horn will sound if any of the landing gears are not down and locked.
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What is indicated by a red light in the landing gear position-indication portion of the annunciator panel?
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The red light indicates that the landing gear is not in a safe condition for landing.
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What information is given to a pilot to indicate that all of the landing gears are down and locked?
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The green lights are used on most aircraft to indicate that all three landing gears are down and locked.
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What is the most likely cause of a landing gear warning system failing to warn when the landing gear is not down and locked?
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A faulty or misadjusted Microswitch.
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How is ice kept from forming on the pitot tube of an airplane?
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Pitot tubes are heated by electric current flowing through heater elements built into them.
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How can you tell, on a preflight inspection, that the pitot heater is operating?
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Turn it on for about a minute and then on the walk-around inspection, feel it to see that it is warm.
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Where can you find the correct part number for the electrically heated pitot head used on an aircraft?
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In the illustrated parts manual for the aircraft.
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If the pitot head includes ports for the static air system, what must be done after the head is replaced?
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A static system leak test must be performed and the results recorded in the aircraft maintenance records.
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Why is it important that ice not be allowed to build up on airplane wings in flight?
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Ice distorts the shape of the airfoil and destroys the aerodynamic lift. The weight of the ice loads the aircraft down.
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Are pneumatic deicer boots operated before ice forms, or after it has formed?
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Pneumatic deicer boots are not operated until ice has formed over them. What the boot inflates, it breaks the ice, and the air flowing over the airfoil blows it away.
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Where does the air come from to operate the pneumatic deicer boots on a reciprocating-engine powered airplane?
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From the discharge side of the air pump used to operate the gyro instruments.
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What is meant by a wet vacuum pump?
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It is a vacuum pump that uses engine oil to lubricate its steel vanes. A dry vacuum pump uses carbon vanes, and it does not required any oil for lubrication.
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What is the purpose of the oil separator in a deicer system?
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Oil separators are used with wet vacuum pumps to remove the lubricating oil from the discharge air before this air is used in the deicer boots.
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What are rubber deicer boots cleaned?
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By washing them with mild soap and water.
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How are rubber deicer boots attached to the leading edges of aircraft wings and tail surfaces?
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They are bonded to the surface with an adhesive. Boots on the older aircraft were attached with machine screws and Rivnuts.
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How is ice prevented from forming on the windshield of modern jet transport airplanes?
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The windshield has a heater element embedded in it. Electric current heats the windshield and keeps ice from forming on it.
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What are two ways rain can be kept from obstructing the pilot's vision through the windshield of an airplane?
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The rain can be blown away by high velocity blast of compressor bleed air, or it can be wiped away with electrically or hydraulically operated windshield wipers.
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When should rain repellent be used on an airplane windshield?
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Only when the windshield is wet with rain.
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Where can you find the instructions for adjusting the tension for the windshield wiper blades?
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In the aircraft maintenance manual.
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What type of fire extinguishing agent is best for both cabin fires and engine fires?
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Halon 1301.
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What is a major disadvantage of "CB" fire extinguishing agent for extinguishing aircraft fires?
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It is corrosive to aluminum and magnesium.
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Why is carbon tetrachloride not recommended as a fire extinguishing agent?
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Carbon tetrachloride produces phosgene, a deadly gas, when it is exposed to flames.
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What is used as a fire extinguishing agent in most of the high-rate discharge systems installed in aircraft?
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One of the halogenated hydrocarbons, such as Halon 1301, pressurized with nitrogen.
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How can you determine the state of charge of a CO₂ fire extinguisher?
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By its weight.
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How can you determine the state of charge of a freon fire extinguisher container?
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By the pressure shown on the built-in gage.
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How does the ambient temperature effect the pressure shown on the pressure gage on a freon fire extinguisher?
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The higher the temperature, the high the pressure.
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What releases the fire extinguishing agent in a high-rate discharge bottle?
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An electrically ignited powder charge blows a knife through a seal in the HRD bottle.
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What precaution must you observe when checking the electrical squib of an HRD fire extinguisher bottle for electrical continuity?
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It takes only a small amount of current to ignite the powder charge, and the method of testing must not send this amount of current through it.
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Does a thermocouple fire detection system warn the pilot of a general overheat condition?
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No, it operates on the rate of temperature rise, and it detects only a fire.
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Does a thermal switch fire detection warn the pilot of a general overheat condition?
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No, it actuates only when there is a fire.
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How is a thermoswitch fire detector circuit checked?
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Close the test switch. If the system is continuous and not shorted, the fire-warning light and bell will actuate.
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How is a continuous-loop fire detector circuit checked?
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Close the test switch. If the system is continuous and not shorted, the fire-warning light and bell will actuate.
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Does a pneumatic fire detection system warn the pilot of a general overheat condition?
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Yes, it actuates when there is a fire or a general overheat condition. |
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How is the pneumatic fire detection system tested?
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When the test switch is closed, low-voltage AC flows through the stainless steel tube in which the gas absorbing element is housed. This current heats the element which releases gas and actuates the fire warning light and bell. |
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What happens when the Fire-Pull T-handle is pulled in a jet transport aircraft?
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The bottle discharge switch is uncovered and armed, the generator field relay is tripped, fuel is shut off to the engine, and hydraulic fluid is shut off to the pump. The engine bleed air is shut off and the hydraulic pump low-pressure lights are deactivated.
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What must be done to release the fire extinguishing agent after the Fire-Pull T-handle has been pulled?
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The Bottle Discharge switch must be closed.
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What type of fire extinguisher is recommended for extinguishing a brake fire?
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A dry-powder type extinguisher.
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How can you determine whether or not a built-in fire extinguishing system has been discharged?
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By checking the blowout plugs on the outside of the aircraft near the extinguisher agent bottles. |
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What is indicated if the red disk in a built-in fire extinguishing system is blown out?
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The agent bottle has been discharged because of an overheat condition.
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What is indicated if the yellow disk in a built-in fire extinguishing system is blown out?
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The agent bottle has been discharged by the flight crew actuating the Bottle Discharge switch.
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