Wood structures Flashcards
(21 cards)
what forms of wood, other than solid wood, are used in aircraft
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
it is usually made of an odd number of thin plies, or veneers, with the grain of each layer placed 90 degrees with the adjacent ply or plies
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 types of glues are used in aircraft wood structure repair
casein glue, plastic resin glue, resorcinol glue and epoxy adhesives
what effects do room temperature have on gluing wood structures using resin glue
curing time as well as joint strength
when are mineral streaks applicable
if inspection fails to reveal any decay
are hard knots acceptable
yes, within specified limitations
why is compression wood not acceptable
it is very detrimental to strength
why is it necessary to examine all stains and discoloration carefully
to determine whether or not they are harmless, or preliminary or advanced decay
why are light steel bushings sometimes used in wooden structures
to prevent crushing the wood when the bolts are tightened
what are the results of insufficient gluing pressure
thick glue lines and 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 members
a scarf joint
why does the strength of beveled scarf joint depend on the accuracy of the beveled cut
the effective glue area will be reduced if both beveled cuts are not the same
always splice and reinforce plywood webs with what type of wood
the same type of plywood as the original
what method will prevent a patch and a plywood pressure plate from adhering together due to extruding glue from the patch
the use of waxed paper between the patch and the pressure plate
what areas of a wood spar may not be spliced
under a wing attachment, landing gear, engine mount, and lift strut fittings
what is the maximum number of splices that should be made to any one spar
two
what is the minimum temperature for curing wood joints with resin glue
70 degrees
