Wood Structures Flashcards
What forms of wood, other than solid wood, are used in aircraft?
Laminated and plywood
How is aircraft plywood constructed?
It is usually made of an odd number of thin plies, or veneers, with the grain of each layer placed 90° with the adjacent ply or plies
What is a laminated wood assembly?
Two or more layers glued together with the grain of all layers approximately parallel
What species of wood is used as a standard for strength properties?
Spruce
How would you inspect wood for rot?
Inspect for a dark discoloration of the wood surface or gray stains along the grain
What type of glues are used in aircraft wood structure repair?
Casein glue, plastic resin glue, resorcinol glue, and epoxy adhesives
What effects does room temperature have on gluing wood structures using resin glue?
Curing time as well as joint strength
When are mineral streaks acceptable?
If inspection fails to reveal any decay
Are hard knots acceptable?
Yes, within specified limits.
Whys is it necessary to examine all stains and discoloration carefully?
To determine whether or not they are harmless, preliminary, or advanced decay
Why is compression wood not acceptable?
It is very detrimental to strength
Why are light steel bushings sometimes used in wood structures?
To prevent crushing the wood when the bolts are tightened
What are the results of insufficient gluing pressure?
Thick glue lines and a weak joint
What methods are used to apply pressure to wood glue joints?
Clamps, elastic straps, weight, vacuum bags, brads, nails, screws, or the use of electric and hydraulic power presses
What type of joint is generally used in splicing structural memebers?
A scarf joint
What is the maximum number of splices that should be made to any one spar?
Two
Why does the strength of a beveled scarf joint depend on the accuracy of the beveled cut?
the effective glue are will be reduced if both beveled cuts are not the same.
Always spice and reinforce plywood webs with what type of wood?
The same type of plywood as the original
What areas of a wood spar may not be spliced?
Under a wing attachment, landing gear, engine mount, and lift strut fittings
What method will prevent a patch and a plywood pressure plate from adhering together due to extruding glue from the patch?
The use of wax paper between the patch and the pressure plate
What is the minimum temperature for curing wood joints with resin glue?
70°F
