Wood Preparation and Aircraft Construction

Question 1

What four time periods are critical to the bonding process of almost all types of adhesives?

Answer 1

1.Pot Life 2.Open assembly time 3.Closed assembly time 4.Pressing time

Question 2

The basic criterion for any aircraft repair is that the repaired structure must only be as strong as the original structure, but the (?)
of the structure and the (?)
shape must also be equivalent.

Answer 2

a. Rigidity b. Aerodynamic

Question 3

List 7 of the most common types of wooden spars.

Answer 3

1. Solid wood rectangular wood spar 2. Solid wood routed I-beam spar 3. Laminated internally routed box spar 4. Laminated spar horizontal 5. Laminated spar vertical 6. Built up box spar 7. Built up I-beam 8. Built up C-spar

Question 4

In a solid wood structure (not a spar), what minimum bevel angle is required for a scarf splice joint

Answer 4

1-10 or 1-12

Question 5

What are the three most important requirements for a strong and durable structural bond?

Answer 5

Preparation Utilization Performing

Question 6

Wood preparation

Answer 6

Cleaning with Naphtha gas is recommended. Sandpaper should never be used as sand can contaminate the wood.

Question 7

Signs of fungus attack on wood product

Answer 7

Include softness, swelling when wet, excessive shrinkage when dry, cracking, discoloration, and a musty or moldy smell.

Question 8

What causes compression failures (i.e., cracks in a wooden structure)?

Answer 8

Wrinkles or streaks across the grain line caused by mechanical stress on the wood after the annual rings have grown.

Question 9

What can the density of wood best be described as?

Answer 9

Weight per unit volume of a substance.

Question 10

What type of wooden spar carries the greatest loads of any of the wooden spars?

Answer 10

Built up wooden box spar

Question 11

What are the maximum splices allowed on a wing spar?

Answer 11

2 Maximum.

Question 12

A built-up I-beam spar repair requires a (?)
scarf joint between the original spar and new material

Answer 12

10 to 1 or 12 to1

Question 13

Should you sand a wooden joint before you apply the adhesive (glue) to a repaired joint in a wooden aircraft structure?
Question 18 options:
a)
Yes
b)
No

Answer 13

No

Question 14

Where on an aircraft wooden structure must drain grommets be placed in the wing area?

Answer 14

All wings must incorporate drainage grommets at the lowest part of each rib bay to drain accumulated moisture

Question 15

Kiln

Answer 15

Reduces moistures and kills insect and decay producing organism.

Question 16

Slope of the grain

Answer 16

A deviation of 1:15 is allowed. The slope of the grain must not be steeper than 1:15.

Question 17

Sitka spruce

Answer 17

The most common type of wood used in aircraft construction.

Question 18

Three most common forms of wood used in aircraft construction

Answer 18

Solid wood, Plywood, Laminated wood.

Question 19

Ideal moisture content for serviceable aircraft wooden structures

Answer 19

Between 8% and 16%, with an ideal range of 10% to 12%.

Question 20

To make sure annual growth rings are at the correct angle to the wide face, at what angle are quarter-sawn wood cut from quartered logs?

Answer 20

45 degrees

Question 21

It is important to observe the orientation of the wood grain to avoid applying glue to the end grain. In relation to the direction of the grain, at what degree is end grain wood cut?

Answer 21

90 degrees

Question 22

List 5 reasons why wood is used in aircraft.

Answer 22

Attributes similar to that of metal and composites
Light weight
low cost
High strength
Minimum of special tools and equipment to maintain and repair

Question 23

What should be the specific gravity of aircraft wood? What should be the specific gravity of aircraft spruce?

Answer 23

From 0.34 to 0.40; 0.36

Question 24

What is the grain deviation or slope allowed in aircraft construction?

Answer 24

1:15.

Question 25

What 8 defects are not allowed in aircraft wooden structures?

Answer 25

1. Cross grain
2. Wavy, curly, and interlocked grain
3. Hard knots
4. Pine knot clusters
5. Spike knots
6. Pitch pockets
7. Mineral streaks
8. Checks, shakes, and splits.

Question 26

What 5 defects may be acceptable depending on their size, location and condition?

Answer 26

1 Cross grain
2 Wavy, curly, and interlocked grain
3 Hard knots
4 Pine knot clusters
5 Pitch pockets

Question 27

For wing spars repair it is necessary to use?

Answer 27

Always use the manufactures repair instructions when available

Question 28

Scarfed Patch is what?

Answer 28

This is the most desired skin patch as it makes the least change in skin thickness or rigidity

Question 29

Since most adhesives will not bond satisfactorily to sealers, it is necessary to avoid applying sealer over the areas where adhesive will be applied. when doing this it is important to?

Answer 29

Mask off areas to receive adhesive, and allow an additional ¼inch on each side of the adhesive area to provide for misalignment when mating the parts.

Question 30

Sealing of bolt heads?

Answer 30

The sealer must be allowed to dry or cure thoroughly

Question 31

5 types of Inspection Methods

Answer 31

1.Tapping 2.Probing 3.Prying 4.Smelling 5.Visual

Question 32

Mineral lines are acceptable true or false

Answer 32

true

Question 33

Reddish streaks are common in Sitka spruce due to?

Answer 33

Due to Deposit in ray cells. They do not affect the quality of the wood

Question 34

Specific Gravity of A/C grade wood should be from

Answer 34

0.34 to 0.40, Ideal is 0.36