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118 Cards in this Set
- Front
- Back
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What species of wood is used as a standard for strength properties of other species of wood used in aircraft structures?
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Spruce is used as the standard of which all woods are compared.
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What type of wood quality must be used in the repair of aircraft structures?
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The wood must be of aircraft quality and equivalent to its original strength or greater.
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What is the differnece between laminated wood and plywood?
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Laminated wood and plywood consist of two or more layers of wood which have been glued together. Laminated wood has the grain of all layers approximately parallel. The grain of plywood runs 90 degrees with the adjacent ply.
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What are two types of glue used for aircraft wood structure repair?
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They are casein and synthetic resin glue. The resin glues that are recommended for wooden aircraft applications are the resorcinol formaldehyde type glues
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What method is used to prepare plywood for bending?
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The wood is soaked in hot water, and then placed in a form until completely dry
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What are the results of using insufficient gluing pressure when making a wood joint?
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The results will normally be thick glue lines, which indicated a weak joint
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How long should a wood glue joint be kept under pressure before removing the clamps?
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The pressure time will vary depending on the temperature of the curing room. The curing temperatures are from 70 degree F and up, Higher temperatures will cause the glue to set faster. To be certain that a glue joint is satisfactory, it is recommended that it remain under pressure at about 85 degrees F for a period of at least seven hours. Full joint strength will develop only after conditioning for at least two days
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What are some of the various methods used to apply pressure to joints in aircraft gluing operations?
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Brads, nails, screws, clamps, or hydraulic and electric power presses
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Why does the strength of a scarf joint depend upon the accuracy of the two beveled surfaces?
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Because an inaccurate bevel will reduce the amount of effective glue area
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What type of patch is preferred for repair of stressed plywood skin and why?
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A properly prepared and inserted scarf patch is the best repair for plywood, and is preferred for most skin repairs. It differs from a splayed patch in that the edges are scarfed to a 12 to 1 slope instead of a 5 to 1 slope, and it uses reinforments under the patch where the glue joints occur
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Are mineral streaks acceptable in aircraft wood?
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Yes, providing careful inspection fails to reveal any decay
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How can the moisture content of wood be determined?
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One way is to use a moisture meter. However, the most accurate method is to take a sample of the wood, weigh it, dry it in a oven at a temperature of 100-105 degrees Celisius, reweight it, and then compute the moisture content by using the following formula
[(W1-W1)/W2]x100 |
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What are of the wood spar may not be spliced?
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It may not be spliced under wing attachment fittings, landing gear fittings, engine mount fittings, or lift-and-interplane strut fittings
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What type of joint is generally used in splicing structural members in aircraft?
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a scarf joint
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What is compression wood and why is not acceptable for aircraft structures?
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Compression wood is wood that is characterized by high specific gravity and has the apperance of an excessive growth of summer wood(hard, non-porous). The defect is difficult to recognize and is very detrimental to strength. Reject all material containing compression wood
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What are three forms of wood?
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Solid, ply, and laminate
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What are two forms two forms of wood that are acceptable for the repair of wooden aircraft skin?
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The plywood and laminated wood are preferred for this application
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What would be the greatest amount of splices placed into one spar?
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Two
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What determines the required quality and strength of fabric that is to be used for covering aircraft?
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The required stength and quality of aircraft fabric is determinded by the pounds per square foot and wing loading (PSF), and the never-exceed airspeed and the aircraft (VNE).
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When anti-tear strips recommended and where are they used?
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Anti-tear strips are installed over the rubs, longerons, and stringers but are under the reinforcing tape before the fabric is installed. They are recommended for all areas in the slipstream.
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What is the maximum permissible deterioration of aircraft fabric before it is considered unairworthy?
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Fabric covering is considered unairworthy when it deteriorates more than 30% from its original required tensile strength
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What should be the strength of the fabric used for re-covering an aircraft?
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All fabric, surface tape, reinforcing tape, thread and lacing cord used to re-cover or repair an aircraft covering should be ofhigh grade aircraft textile material. The material must be at least as good quality and of equivalent strength as those originally used by the aircraft manufacturer
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What is purpose of and location of drain grommets in aircraft fabric?
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They allow the condensed moisture to leave the aircraft as well as furnish ventilation. Drain grommets are located on the underside of airfoils at the trailing edge as close to the rib as practical, and at the lowest point along the center of the underside of each fuselage bay
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What is the purpose of reinforcing tape?
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Reinforcing tape is used over all stitching and prevents the stitching cord from tearing through the fabric.
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What type of fabric is not affected by moisture or mildew?
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Fiberglass fabric is not affected by moisture, mildew, chemicals, and most acids
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What method are used to check the strength of doped fabric?
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A fabric punch test (Maul Test) will provide a general indication of the strength of the fabric, but if a punch tester indicates that the fabric strength is marginal, a laboratory test should be performed to determine the actual strength of the fabric.
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What type of machine-sewed seems are used in aircraft covering?
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Plain overlap seams, folded-fell seams, and french-fell seams
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What should be done with structures that will come in contact with doped fabric?
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Treat all parts of the structure that will come in contact with doped fabric with a proctective coating such as aluminum foil, dope proof paint, or cellulose tape.
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If the original rib stitch spacing cannot be determined when re-covering an aircraft, where can you find the rib stitch spacing that should be used?
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Use the rib stitch spacing chart in the AC 43.13-1B
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What is the standard tie-off knot used during rib stitching?
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A modified seine knot is used to tie off all stitches except the starting stitch
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What do you call the edge of the cloth, tape, or webbing that been woven to prevent raveling
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Selvage edge
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The type of fabric used for covering aircraft are organic and synthetic. Name two organic and two synthetic types.
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The organic fibers are cotton and linen. The synthetic fiber include fiber glass and heat shrinkable synthetic fiber such as nylon and Dacron
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When covering aircraft, where is surface tape used?
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Sewed seams, lapped edges, and all stitching is covered with surface tape. The surface tape has a pinked-edge to prevent unravelling during the installation process
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Name the advantages of using the envelope method to cover fabric aircraft.
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It saves labor because practically all sewing is done by machine. It is similar to pulling a sock over the wing. The only stitching left to do would be to the structure.
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Name the safety and health precautions to be observed in operating a dop room, including storage of material.
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The dope room should be well lighted and ventilated using spark proof motors, lights, and switches. All flameable material should be stored in fireproof containers in protected areas. Dope and paint rooms that are not located in a spate building should be isolated from the rest of the building by metal partitions and fireproof doors.
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What type of test can be preformed to identify exsisting paint finish?
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Apply a coat of engine oil to a small area. Nitrocellulose will soften in a few minutes, but acrylic and epoxy will show no effects. If not identified. next wipe doen a small area with MEK. MEK will pick up pigment from an acrylic finish, but will not affect an epoxy coating.
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What causes blushing when applying dope or lacquer, and how can it be prevented?
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When doping is accomplished under humid conditions, blushing is possible. Rapid evaporation of thinners and solvents lower the temperature of the surface of the wet dope casuing condensation of moisture from the air. The moisture causes a milky white or cloudy apperance known as blush. The condition may be elimnated by heating the room to decrease the humidity, or by using a blush-retarding thinner to increase the drying time. Blushing is also caused by moisture in the air supply, drafts, or change in temperature.
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What is the purpose of using fungicidal dope when finishing aircraft fabric?
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To prevent micro-biological deterioration (rotting) of the fabric
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What are the identification marking requirments for United States registered fixed wing aircraft?
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The Roman capitol letter "N" followed by the registration number must be displayed on both sides of the fuselage, or on both sides of of the vertical tail surfaces. The height of the characters must be equal in size and be at least 12 inches, and the characters must be 2/3 as wide as they are high. The exceptions to the width rule are the number "1", which must be 1/6 as wide as it is high, and the letters "M" and "W", which may be as wide as they are high. Characters must be formed by solid lines 1/6 as thick as they are high, and the spacing between each character may not be less than 1/4 of the character width.
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What are two types of dope used for aircraft finishes?
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They are nitrate and butyrate
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What is the advantage of butyrate over nitrate?
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Less flammable
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What would happen if dope was ever used over paint or enamel?
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It would have the tendency to lift and remove such materials.
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What is applied to metallic surface as a common resistant covering before the application of enamel or lacquer?
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Zinc chromate primer is normally used for this purpose.
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What are the most common methods of applying aircraft finishes?
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They are dipping, brushing, or spraying
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What type of paint may be used over any paint system that is in a good condition?
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Epoxy topcoats will adhere to all paint systems that are in good condition and bay be used as a general touchup, including touchup of defects in baked enamel coatings
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What normally causes runs and sags in a spray application of a paint finish?
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Hold the gun too long in one place or holding the gun to close can cause to much paint to be applied in one area.
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What causes an "orange peel" or "pebble" finish?
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Incorrect spray gun setting, incorrect air pressure, incorrect paint viscosity, and hold the gun too far from the work.
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What is used to thin chromate primer?
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Toluene
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Which federal regulation presribes the size and location requirements for aircraft indetification numbers?
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FAR Part 45
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What type of materials should be thoroughly protected when using paint remover?
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Synthetic rubber surfaces, aircraft tires, fabric, and acrylics must be protected against possible contact with paint remover.
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What is the grip length of a rivet?
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The grip legth is the combined thickness of the material to be joined by the rivet.
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Where are special rivets , such as Huck or Cherry lock rivets used?
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They are used in places where access to both sides of the riveted structure is impossible, or where limited space will not permit the use of a bucking bar. These rivets require special tools, installation, and removal procedures. They are commonly called blind rivets
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What is bonded honeycomb (sandwich) construction?
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It is a laminar construction construction consisting of a combination of alternating dissimilar materials, assembled and fixed in relation to each other so that the properties of each can be used to attain specific structural advantages for the whole assembly while reducing weight.
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What types of materials are used in honeycomb construction?
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Honeycomb construction may employ stainless steel, titanium, magnesium, plywood, resin=impregnated paper, E-glass, nylon, or cotton cloth in various combinations
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Where are sandwich construction assemblies used?
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They are used for such areas as bulkheads, control surfaces, fuselage panels, wing panels, radomes, empennage skins, or shear webs.
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What procedures should be to prevent damage to the hole when drilling through Plexiglass?
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The Plexiglasshould be backed with wood and the feed slowed as the drill point break through the underside of the sheet. A drill bit that is to be used for this purpose should be modified to a 60 degree tip angle, the cutting edge to a sero rake angle, and the back lip clearance angle increased to 12-15 degrees.
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What calculations must be made when bending sheet metal?
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Bend allowance and setback must be determined. Set back depends on two factors: (1) radius, (2) thickness. Bend allowance depends on four factors; (1) the degree of bend, (2) the radius of the bend, (3) the tickness of the metal, and (4) the type of metal used. The amount of material required for the bend must be determined to assure that the final dimensions will be correct. Bending a strip of metal compresses the material on the inside of the curve, and stretches the material on the outside of the curve. However, in the approximate center between these two extremes is a space that is neither stretched nor compressed which is called the neutral axis. When making a bend to exact dimensions, the length of the neutral line must be calculated so enough material can be allowed for the bend.
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What factors are used to determine setback?
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The radius of the bend and the thickness of the material. Setback = Radius + Thickness
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What is joggle?
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A joggle is an offset near the endge of a piece of sheet metal to allow clearance for a sheet or extrusion
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What are several methods used in forming sheet metal?
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Folding, bumping, crimping, shrinking, and stretching
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What is crazing and how does it occur?
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Hairline cracks in the surface of plastic. A form of heat damage caused by uneven heating, one side expanding more than the other casuing excessive stress. Subjecting plastic to large stresses and exposure to harmful solvents will cause crazing.
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Briefly describe the anodizing process and what purpose is serves.
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Aluminum alloys are placed in an electrolytic bath which causes a thin film of hydroxide to form on the surface of the aluminum. This anodized coating not only provides excellent resistance to corrosion, but it is also an excellent bond for paint.
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What are the proper dimensions for the shop head of a rivet?
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1 and 1/2 times the diameter in width and 1/2 times the diameter in height after bucking.
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When inspecting Plexiglas, what should you look for?
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Crazing and discoloration
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What causes honeycomb structure to delaminate?
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Moisture
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What are the acceptable repair methods for bonded honeycomb structure that has been damaged?
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There are two acceptable methods of repair currently being used on damaged skin and core materials of bonded honeycomb structures. One is the potted repair method. The other is the laminated glass fabric cloth overlay which is applied to honeycomb damage which exceeds the repair limitations of the potted compound method.
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What size drill should be used for the common shank rivet diameters of 3/32 inch, 4/32 inch, and 5/32 inch?
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3/32 rivet = #40
4/32 rivet = #30 5/32 rivet = #21 |
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What is used for hole filling in a bonded honeycomb repair?
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Potting compound
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What is a lightning hole?
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Lightning holes are cut into rib sections, fuselage frames, and other structural parts to decrease weight. Flanges are pressed around the holes for strength
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What type of weld joint must be used to weld magnesium?
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Only butt welds are used to weld magnesium. This is to prevent the possibility of trapping contaminates.
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Why must all flux be removed from the metal after welding magnesium?
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Any flux left on the metal will result in severe corrosion
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What must be done in orderto successfully weld titanium?
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The weld zone must be shielded with an inert gas such as Helium or Argon
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What is gas shielded arc welding?
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A gas is used as a covering shield around the arc to prevent the atmosphere from contaminating the weld
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What are the advantages of gas-shielded arc welding?
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It results in a stronger, more ductile, and more corrosion resistant weld.
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What is an advatage of electric arc welding over gas welding?
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It causes less buckling and warping of the welded material
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What determines the amount of heat that will be applied to the work when welding by the oxy-acetylene method?
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The torch tip's orifice size or diameter
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What will be the result of using a torch tip that is too large or too small?
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If the torch tip is too large, the heat will be to great and holes may be burned in the metal. If the torch tip is too small, the heat provided may be insufficient to produce penetration to the proper depth causing a strength weld.
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How do you determine the correct size filler rod to be used in welding?
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The diameter of the rod be used is governed by the thickness of the metals being joined.Weldingrods are made in standard 36 inche lengths, and in diameters from 1/16 to 3/8 inch. If the rod is too small, it will not conduct heat away from the puddle rapidly enough, and a burned weld will result. A filler rod that is too large will cool the puddle too quickly and not allow the proper penetration.
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What is brazing?
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Brazing is a metal joining process in which the bonding material is a non-ferrous metal with a melting point lower than the metals being used. It includes silver soldering, copper brazing, and aluminum brazing. It can be used to join metals that are damaged by high heat.
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What is one method of controlling expansion when welding a joint?
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By tack welding at intervals along the joint
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Why is it especially desirable to use a soft flame when welding aluminum?
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To avoid blowing holes in the metal when the puddle is formed
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What is the purpose of using flux when welding aluminum?
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Aluminum and its alloys combine with air and form oxides very rapidly, and oxides form doubly fast if the metal is hot. Aluminum welding flux is designed to remove the aluminum oxide by chemically combining with it. Aluminum fluxes dissolve below the surface of the puddle and float the oxides to the surface where they can be removed.
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What is the maximum safe pressure for acetylene gas when welding?
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When acetylene gas is compressed in a container to a pressure greater than 15 psi, it becomes dangerously unstable. At 29.4 psi, acetylene is self-explosive and only a slight shock can cause it to ignite.
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How can dents at a steel tube cluster joint be repaired?
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Weld a specially formed steel patch over the dented area and surrounding tubes.
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What type of flame should be used when silver soldering?
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The flame should be neutral
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What are the procedures for preparing a metal fuel tank for welding?
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The interior of the tank should be washed with hot water and detergent, and then steamed for a minimum of thirty minutes. This procedurewill vaporize and removeany residual fuel in the tank. Then fill the tank with Carbon Dioxide gas from a fire extinguisher and seal the tank except for a small vent hole.
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When splicing tubing by the inner sleeve method, what method can used to insert a tight fitting inner sleeve into the replacement tube.
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The inner sleeve can be chilled with dry ice or in cold water, and the outer sleeve can be heated. This will allow for a tighter fit repair.
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Why is fluxed used on silver solder?
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It cleans the base metal of oxide to ensure a good bond
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What are three types of commonly used flight control systems?
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They are the cable, the push-pull tube, and the torque tube systems. The cable system is the most widely used because deflections of the structure to which it is attached do not affect its operation
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What is used metal aircraft to keep control cable tension within acceptable limits?
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Because there is a considerable ifference in temperature expansion between the aluminum aircraft structure and the steel control cables, some large aircraft incorporate cable tension regulators in the control cable systems. These regulators are designed to maintain a given cable tension. The unit consist of a compression spring and a locking mechanism which allows the spring to make corrections in the system only when the cable system is in neutral.
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What is fairlead?
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It is a cable guide used to guide cables in a straight line through or between structural members of the aircraft. Deflection of the cable caused by a fairlead is undesired due to causing resistance of the controls. Fairlead should never deflect the alignments of a cable more than 3 degrees from a straight line.
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Where does failure of control cables occur most frequently?
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Breakage of wire strands occur most frequently where cables pass over pulleys and through fairleads.
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Which flight control surface are considered the primary group?
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The elevators, the ailerons, and the rudder
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Which flight controls are considered the secondary group?
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The trim tabs, spring tabs, wing flaps, servo tabs, and the anti-servo tabs. They do not alone cause totation of the aircraft about its axes
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Which flight controls are in the auxiliary group?
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This group consists of the flaps, speed brakes, spoilers, slats, leading edge flaps, and slots.
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How do wing flaps affect landing speed and approach angle of an aircraft?
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The use of flaps increase the camber of a wing and therefore the lift of the wing, making it possible for the speed of the aircraft to be decreased without decreasing the lift produced by the wing. This permits a steeper glided angle and lower speed to be obtained for the landing approach.
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What is balance tab?
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It is an auxiliary control with fixed linkage that is designed in such a way that when the primary control surface is moved the tab moves in the opposite direction. Aerodynamic forces (back pressure) acting on the tab assists the pilot in the moving the control surface.
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What is a trim tab?
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It is an auxiliary control attached to the trailing edge of the primary control surface that is positioned by movement of a cockpit control to reduce the workload on the pilot in maintaining a desired flight attitude.
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What is the purpose of the collective pitch control is a helicopter?
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It is used to change the pitch of the main rotor blades therefore increasing or decreasing lift.
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What unit on a helicopter is used to compensate for torque created by the main rotor?
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The tail rotor
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What control operates the helicopter tail rotor?
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The anti-torque pedals
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What are the three axis of an aircraft, and which control surfaces cause the aircraft to move about each axis?
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They are the longitudinal, the lateral, and the vertical. The longitudinal axis extends from nose to tail and uses ailerons for roll. The lateral axis extends from wingtip to wingtip using the elevators for pitch. And the vertical axis passes through the center of the airframe from top to bottom, and uses the rudder for yaw.
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When installing an aircraft bole, what precaution would you take regarding the position of the bolt?
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Where possible, the bolt head should be positioned on top when a bolt is installed vertically, and the bolt head should be forward when it is installed horizontally. In there positions the bolt is less likely to slide out if the locking device fails.
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How is the propeller torqu corrected during assembly and rigging in some single engine aircraft?
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Some aircraft have the leading edge of the vertical stabilizer offset to the longitudinal center line to conteract engine torque.
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What reference publication should be used to rig aircraft, including the control system?
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You should refer to the Aircraft Specifications ot Type Certificate Data Sheets issued by the FAA, and also do to the Maintenance Manual issued by the manufacturer
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What are vortex generators?
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Small, low-aspect-ratio airfoils mounted on the upper surface of wings. Their function is to dampen shock-induced separation of the airstream which results in a stall
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What is a servo tab?
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A cockpit controlled adjustable tab attached to the trailing edge of a primary control surface. The tab moves opposite the direction of the control surface producing an aerodynamic force that moves the primary
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What factors are used to determine the proper cable tension?
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The size of the cable and the outside temperature
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What needs to be done to prepare an aircraft for an annual and 100 inspection?
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Remove or open all necessary inspection plates, access doors, fairings and cowlings. Then thoroughly clean the aircraft and the engine
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What is the difference between an annual and 100 hour inspection?
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Except for the difference in time between inspections and the person who can sign it off, there is no difference between the annual and and the 100 hour inspection. They are indetical in scope and detail.
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Who has the authority to sign off and return to service a 100 hour inspection?
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An appropriately rated mechanic may return an aircraft to serivce after a 100 inspection.
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What are the operating conditions which make the 100 hour inspection mandatory?
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The 100 hour inspection is required for aircraft that carry persons for hire or is used to give flight instructions for hire
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Where can you find a checklist for the 100 hour inspection?
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In FAR Part 43, Appendix D
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Where would you find the recommended statement for recording the approval or disapproval for return to service of an aircraft after a 100 hour inspection?
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In FAR Part 43.11
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Who can approve an aircraft for return to service after an annual inspection?
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An A&P mechanic who holds an Inspection Authorization (IA) certificate
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Who can approve an aircraft for return to service after a progressive inspection has been performed?
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A certified mechanic holding an Inspection Authorization, the aircraft manufacturer, or a certified repair station.
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Does an aircraft being operated under a progressive inspection program require a 100 hour inspection if it is used to give flight instruction for hire?
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No
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What is the maximum time that a 100 hour inspection may be extended?
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Not more than 10 hours. The 10 hours may only be used to ferry the aircraft to the next inspection site.
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