Answers - Aircraft Wood


1. 8‐12%, 20%
2. decay, musty, moldy
3. temperature, humidity, deterioration
4. shear
5. decay, rot, decay
6. water penetration
7. compression
8. sharp or solid
9. spruce
10. plywood
11. softwoods
12. grain direction
13. mineral streaks
14. cracks
15. compression
16. casein glue, plastic resin glue, resorcinol glue, epoxy
17. wetting tests
18. full strength, stress
19. scarf joints
20. wing attachment, landing gear, engine mount fittings.


1. true: a certificated mechanic may not perform work unless he has performed the work concerned at an earlier date.
2. false: ideal range is 8‐12%.
3. true
4. false: Shear loads
5. true
6. false: The condition of the fabric provides an useful indication of the condition of the wood underneath.
7. true
8. true: A soft and mushy area is an indication of rotting.
9. false: Spruce is the preferred choice.
10. false: softwoods
11. true
12. false: Hard knots are acceptable under certain conditions.
13. false
14. true
15. true
16. false: Surfaces should be prepared with a planer or joiner.
17. true
18. false: any point except at wing attachment fittings, landing gear , engine mount, or lift and interplace strut fittings.
19. true
20. true


1. Two or more layers glued together with the grain of all layers approximately parallel.

2. It is usually made of an odd number of thin plies with the grain of each layer at 45 or 90 degrees to the adjacent ply or plies. Laminated wood all grain are parallel.

3. Spruce

4. Inspect for a dark discoloration of the wood surface or gray stains along the grain.

5. Casein (obsolete), plastic resin glue, resorcinol glue, and epoxy resin.

6. Curing time as well as joint strength. Curing time will be shorter and the joint strength will increase.

7. If inspection fails to reveal any decay.

8. Yes, hard knots up to ¾ inch in diameter are acceptable under certain conditions.

9. It is detrimental to strength and is difficult to recognize, compression wood is characterized by high specific gravity.

10. To determine whether or not they are harmless, or preliminary, or advanced decay.

11. prevent crushing the wood when the bolts are tightened.

12. weak and strong areas in the same joint.

13. Clamps, elastic straps, weight, vacuum bags, brads, nails, screws, and electric and hydraulic presses.

14. A scarf joint.

15. The effective glue area will be reduced if both beveled cuts are not the same.

16. The same type of plywood as the original.

17. The use of waxed paper or release films between the patch and pressure plate.

18. Under a wing attachment fitting, landing gear fitting, engine mount fitting, and lift and interplane strut fittings.

19. To provide additional bearing surface.

20. 70 F.

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