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28 Cards in this Set
- Front
- Back
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? |
Because it concentrates stresses and can cause failure. |
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What is the basic difference between laminated wood and plywood? |
Laminated wood grain runs parallel or in the same direction, while plywood grain is layered across at 90 or 45° angle. |
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What effect does moisture have in a wood aircraft structure? |
Causes the wood to swell and crack as it dries out. It also allows fungi 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? |
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? |
Flat grain. |
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How do you detect decay in a wood structure? |
Stick a sharp pointed knife into the suspected area and pry into the wood up. If the wood is good, it will come up as a long splinter. If it's 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? |
No, if there's no evidence of decay in the wood. |
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How is compression wood identified? |
It has a high specific gravity, it appears to have an excessive growth of summerwood, and little contrast between springwood and Summerwood. |
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Is a knot 1/2-inch in diameter allowed if it is in the web of a wing spar? |
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? |
Yes, if they cause only a small effect on grain direction. |
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What kind of glue is recommended for making repairs to a wood aircraft structure? |
Synthetic resin or resorcinol glue |
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What reference material may be used for acceptable repairs to Wood aircraft structure? |
AC 43.13 - 1B chapter 1 |
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How is the scarf on a wing spar reinforced? |
By gluing spruce or birch plywood reinforcement plates on 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 wings spar if the wing attached bolt holes in the spar are elongated? |
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? |
12 times the thickness recommended, 10 times is the minimum. |
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How is aircraft plywood prepared for making a compound bend? |
Soak the wood in hot water until it is pliable. |
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What is used to apply pressure to a glue joint when splicing a wood aircraft wings spar? |
Cabinetmakers' parallel clamps. |
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How much pressure must be applied to a glue joint in a piece of soft wood to produce a strong joint? |
125 to 150 lb per square inch. |
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What kind of repair is recommended for a hole in the plywood skin of an aircraft wing? |
Scarf patch. |
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What is the recommended taper for a splayed patch in the plywood aircraft skin? |
5 to 1 |
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What is the recommended taper for a scarf patch in a plywood aircraft skin? |
12 to 1 |
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Why should sandpaper never be used when preparing a scarf joint in a wings spar for splicing? |
The dust caused by sanding will plug the pores of the wood so the glue cannot get in to form 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? |
1-in in diameter. |
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Why are light steel bushings often used in both holes in a wood Wing spar? |
The bushings keep the spar from being crushed when the knot 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? |
At least 7 hours. |
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Which of the wood Wing spar must not contain any splice? |
Under attachment 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? |
Reinforcing plates are glued to both sides of the splice. |