Section II Airframe Structures (Aircraft Covering) 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 load (PSF), and the never exceed airspeed (VNE) of the aircraft.
Where are anti-tear strips recommended and where are they used?
Anti-tear strips are installed over the ribs, longerons, and stringers but are under the reinforcing tape before the fabric is installed. They are recommended for any area in the slip stream.
What is the maximum permissible deterioration of aircraft fabric before it is considered unairworthy?
When I deteriorates more than 30% from its original required tensile strength.
What should be the strength of the fabric used for recovering in aircraft?
High-grade aircraft textile material. Of good quality and equivalent strength as those originally used by the aircraft manufacturer.
What is the purpose of location of drain grommets in aircraft fabrics?
Do you allow condensed moisture to leave the aircraft as well as furnish ventilation. They’re located on the underside of airfoils at the trailing edge as close to the rib as practical, and at the lowest point along the center of the underside of each fuselage bay.
how are drain grommets installed an 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 types are installed with a second coat of dope, and the drain holes are opened by cutting out the fabric in the center of the grommet.
name the methods of applying fabric to an aircraft wing.
Blanket an envelope method.
What is the purpose of reinforcing tape?
It prevents stitching cord from tearing through the fabric.
What type of fabric is not affected by moisture or mildew?
Fiberglass fabric is not affected.
What methods are used to check the strength of doped fabric?
Use of a Fabric punch test (maul test) if the strength is marginal a lab test should be performed to determine actual strength of the fabric.
What type of machine sewed seams are used in aircraft covering?
Plain overlap seams, folded fell seams, and french fell seams
what should be done with structure that will come in to contact with doped fabric?
Treat all parts of the structure that will come in contact with doped fabric with a protective coating such as aluminum foil, dope proof paint , and or cellulose tape.
If the original rib stitch spacing cannot be determined when recovering an aircraft, where can you find the rib stitch spacing that should be used?
AC 43. 13-1B (rib stitch spacing chart)
what is the standard tie-off knot used during rib stitching?
A modified seine knot is used for all except the starting stitch.
What do you call the edge of the cloth, tape, or webbing that has been woven to prevent unraveling?
Selvage edge.
