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28 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?
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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. |
