Airframe Structures: Aircraft Coverings 🔊 Flashcards
What determines the required quality and strength of fabric that is used for covering aircraft?
It is determined by the pounds per square foot of wing loading (PSF) and the never-exceed airspeed of the aircraft (VNE).
When are anti-tear strips recommended and where are they used?
Under wing ribs stitching when the never-exceed speed (VNE) is greater than 250 mph. It should cover the entire top surface of the wing and underside of the wing in the propeller slipstream.
What is the maximum permissible deterioration of aircraft fabric before it is considered unairworthy?
When it deteriorates more than 30 percent from its original required tensile strength.
What should be the strength of the fabric used for re-covering an aircraft?
All fabric, surface tape, reinforcing tape, thread, and lacing cord used should be of high-grade aircraft textile material. The material must be at least as good quality and of equivalent strength as those originally used by the aircraft manufacturer.
What is the purpose and location of drain grommets in aircraft fabric?
They allow the condensed moisture to leave the aircraft as well as furnish ventilation. Drain grommets are located on the underside of airfoils at the trailing edge as close to the rib as practical and the lowest point along the center of the underside of each fuselage bay.
How are drain grommets installed in aircraft fabric?
Brass grommets should be mounted on fabric patches and then doped to the covering. Plastic grommets are doped directly to the covering. Both are installed with a second coat of dope and the drain holes are opened by cutting out the fabric center.
Name the methods of applying fabric to an aircraft wing.
Blanket and envelope method
What is the purpose of reinforcing tape?
It is used under all stitching and prevents the stitching cord from tearing through the fabric.
What type of fabric is not affected by moisture or mildew?
Fiberglass fabric
What methods are used to check the strength of doped fabric?
A fabric punch test (maul test)
What type of machine-sewn seams are used in aircraft coverings?
Plain overlap seams, folded-fell seams, and French-fell seams
What should be done with structure that will come in contact with doped fabric?
Treat all parts with a protective coating such as aluminum foil, dope proof paint, or cellulose tape.
If the original rib stitch spacing cannot be determined when re-covering an aircraft, where can you find the rib stitch spacing that should be used?
Use the rib stitch spacing chart in the AC 43.13-1B
What is the standard tie-off knot used during rib stitching?
A modified seine knot is used to tie off all stitches except the starting stitch.
What do you call the edge of cloth, tape, or webbing that has been woven to prevent raveling?
Selvage edge (this question has been known to be reversed; the answer is sometimes the question)
