Airframe Oral (Jeppesen) Wood, Composite, and Transparent Plastic Structures Flashcards
What are the three forms of wood commonly used in aircraft construction?
Solid, laminated, and plywood.
What type of wood should be used when splicing reinforcing plywood webs?
The same type of plywood as originally used.
Name at least four different types of defects found in wood.
Knots, checks, splits, pitch pockets, cross grain, curly grain, decay, dry rot, etc.
Can a section of wood containing a hard knot be used?
Yes, within specified limits.
What type of glue may have been used in older wooden aircraft construction that requires careful inspection to detect deterioration?
Casein glue.
What are the three types of glues used in modern aircraft construction and repair?
Resorcinol glue, Phenol-formaldehyde glue, and epoxy resin glue.
Is compression wood acceptable for structural repairs?
No.
Why should the various pieces of wood being joined be kept in the same room for at least 24 hours prior to joining?
To allow the moisture content to equalize, thereby minimizing dimensional changes in the wood.
Why is it important to consider the open-assembly time when gluing wooden structures?
If the maximum open-assembly time is exceeded, the joint may fail since the glue may begin setting up before the joint is assembled.
Why is it important to apply the proper clamping pressure to a glue joint?
Clamping forces air out of the joint, brings the wood surfaces together evenly and is in part responsible for the strength of the glue line.
Describe some of the methods used to apply pressure to a glue joint?
Clamps, nailing strips, power presses, brads, nails, and small screws.
What minimum curing temperature should be observed when joining wood with various adhesives?
70 degrees Fahrenheit or as specified by the glue manufacturer.
When inspecting wood structures, why might it be important to consider stains and discolored areas?
Stains and discoloration usually accompany decay and/or rot.
Describe the acceptable methods used to repair elongated bolt holes found in a wooden wing spar.
Remove the section containing the elongated hole{s} and splice in a new section or replace the entire spar.
What type of joint is used to splice a solid or rectangular wood spar?
A scarf joint.
In what areas are splices to a wood spar prohibited?
Under an attachment fitting for the wing root, landing gear, engine-mount, lift, or inter-plane strut.
What is the maximum number of splices allowed for any single spar?
Two
Describe the characteristics of a scarf joint.
The pieces to be joined are tapered or beveled on a slope of 1 to 10 or to 12.
Why must the beveled cut be accurate on both pieces of wood being repaired with a scarfed joint?
The two pieces must match exactly to ensure a tight glue joint.
What are the two primary uses for plywood in aircraft construction?
Gusset {or reinforcing} plates and aircraft and aircraft skin.
Provide examples of at least three types of plywood skin repairs.
Splayed patches, surface patches, plug patches, 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 / 10th inch thick?
A splayed patch may be used if the hole can be cleared out to a diameter of less than 15 thicknesses of the skin.
What should be done to prevent a plywood patch and the pressure plate from sticking together if glue is extruded from the joint?
Place a piece of waxed paper or vinyl plastic between the patch and the pressure plate.
Why are lightweight steel bushings sometimes used in wooden structures?
Bushings prevent the wood from being crushed when bolts are tightened.
