Wooden Structures

Question 1

What is a liminated spar

Answer 1

strips of wood are glued together with their grain running in the same direction. Should have the same strength as a solid spar

Question 2

What is a front / fear spar

Answer 2

Primary component
Carry all the stresses
Carry main load
Made of limiated wood

Question 3

What is a compression strut

Answer 3

Separates the front and rear spar

Made of aluminium tubing.

Question 4

What is a drag wire

Answer 4

Prevents front spar from travelling rear wards under any load , bolted to front spar

Question 5

What is anti drag wire

Answer 5

Stops rear spar travelling front wards under a load

Question 6

Box spar wing

Answer 6

A box structure built between the spars stiffens the spars so they can carry all of the bending and torsional loads to which the wing is subjected in flight.

Question 7

What are the causes of failures

Answer 7

Chemical reactions
Ageing 
Moisture 
Shrinking 
Fungu
Oil and fuel leaks 
Drain holes blocked

Question 8

Preservation

Answer 8

Long

Question 9

Surveying

Answer 9

Wood needs to be dry
Be aware of smells
Look for warping misalignment and structural failure
Musty smell indicates fungal groth

Question 10

What does splinters mean

Answer 10

Would fail

Question 11

What dose no splinters mean

Answer 11

Glue failure

Question 12

What do you do if no inspection advise exists

Answer 12

Go to manufacture or CAA

Question 13

Inspection of glue joints

Answer 13

Protective coating removed
Use magnifying glass and stipled feeler gauge to prope the joint
If the joint is penetrated the glue joint is defective

Question 14

Shrinkage

Answer 14

Induced stress on members causes loosens of attachment

Question 15

Elongated bolt holes

Answer 15

Check for looseness , steel bushing can be fitted

Question 16

Compression failures

Answer 16

Ruptured across the fibers can be detected by shining a touch parallel to the grain structure

Question 17

What does dark discolouring or grey streaks show

Answer 17

Water penitration

Question 18

Seasoning of timber

Answer 18

After cutting stack for 60 days to allow moisture to evaporating further carried out in drying sheets for one to three years
Protective coverage can be applied

Question 19

What is the moisture content of timbre

Answer 19

15%+- 2%

Question 20

How is Brittleness measured

Answer 20

Teasted using time drop weight or izod test

Question 21

What is splitting test

Answer 21

With a blunt chisel to reveal the grain structure

Question 22

What should the rate of groth

Answer 22

Less than 6 rings per 25mm should be rejected

Question 23

Testing recording

Answer 23

Test piece should be kept for no more than 2 years

Question 24

What is dotes diese

Answer 24

At the base of trunk

To elimate tree is cut 10 m above the trunk

Question 25

Plywood

Answer 25

Light sanding direction of grain

Should be removed

Question 26

Timber

Answer 26

Suitable roughing for keying adhesive

Question 27

What must joints be free of

Answer 27

Oil and grease

Question 28

What should you be carful of when glueing joints

Answer 28

To not squeeze joints

Question 29

How long should joint get dried for for full strength

Answer 29

Dry for 2 days

Question 30

How long should joint be dried for for maximum resistance to moisture kept at in room temp

Answer 30

2-3 weeks

Question 31

Test samples

Answer 31

The fractured glue faces should show at least 75% of wood fibres, evenly distributed over the fractured glue surfaces

Question 32

Wet tests

Answer 32

Tests should only be carried out on joints which have been conditioned for 2 to 3 weeks