Wood Structures Flashcards
How would you inspect wood for rot (decay)?
Inspect for a dark discoloration of the wood surface or gray stains along the grain.
What three forms of wood are used in aircraft?
Solid, Laminated and Plywood.
What is a laminated wood assembly?
two or more layers glued together with the grain of all layers
approximately parallel.
How is aircraft plywood constructed?
Made of an odd number of thin plies, and the grains of each layer,
placed 90° with the adjacent ply or plies.
What specie of wood is used as a standard for strength ?
Spruce. (Madeira de Abeto)
Are hard knots acceptable?
yes, with limits
Why is compression wood NOT acceptable?
It is very prejudicial to strength.
When are mineral streaks acceptable?
If the inspection fails to reveal any decay.
Why is it necessary to examine all strains and discoloration?
To determine if the stains are harmless, preliminar or advanced decay
What types of glues are used in aircraft wood structure repair?
Casein, Epoxies, Phenol-formaldehyde, Resorcinol Glue.
What type of glue may have been used in OLDER AIRCRAFT construction that requires careful inspection
to detect deterioration?
Casein Glue.
What types of glues are used in MODERN AIRCRAFT wood structure repair?
Resorcinol glue, Phenol-formaldehyde glue and Epoxi resin glue.
What is the minimum °F for curing wood joints with resin glue?
70°F or as specified by the glue manufacturer.
Why it is important to consider the open-assembly time when gluing wooden structures?
Because if the maximum open-assembly time is exceeded the joint may fail since the glue my begin setting up before
the joint is assembled.
Why it is important to apply the proper clamping pressure to a glue joint?
Clamping forces the air out, brings the wood surfaces together evenly and in part responsible for the strength of the
glue line
Describe the acceptable methods used to repair enlongated bolt holes found in a wooden wing spar:
Remove the damaged section and splice in a new section or replace the entire spar.
Describe the characteristics of a scarf joint:
The pieces to be joint are tapered or beveled on a slope of 1 to 10 or 1 to 12.
What are the results of insuficient gluing pressure?
Thick glue and a weak joint.
What methods are used to apply pressure to wood glue joints?
Clamps, Brads, Nails, Elastic Straps, Weight, Vacuum Bags, Screws, Electric and Hydraulic power presses
What type of joint is used in splicing structural members?
scarf joint
What areas of a wood spar may NOT be spliced?
Under a wing attachment, landing gear, engine mount and lift strut fittings.
What are the two primary uses for plywood in aircraft construction?
Gusset plates and aircraft skin.
Provide examples of at least three types of plywood skin repair:
Scarf, surface, plug, splayed and scarfed patches.
What type of patch should be used to repair small holes in thin plywood skin if the skin is less than 1/10
inch thick?
splayed patch