Aircraft covering fabrics are made of materials from what two sources?
Organic materials and synthetic materials.
How would you determine the strength requirements for fabric used to re-cover an aircraft?
The fabric must be of at least the quality and strength of the fabric used by the original manufacturer.
What two types of organic fibers are used for covering aircraft?
Cotton and linen.
What is meant by warp. weft. and bias?
Warp is the direction along the length of the fabric.
Weft is the direction across the fabric at right angles to the warp.
Bias is a direction at a 45 degree angle to the warp and weft.
What is the purpose of the selvage edge on a roll of fabric?
It prevents the fabric from unraveling.
What identification marking is found on the selvage edge, and in which direction is the warp applied?
The FAA-PMA stamp is found on the selvage edge and the warp is applied parallel to the line of flight.
How are the fabric type and strength requirements determined for fabric-covered aircraft?
The original manufacturer determines the fabric type and the strength requirements are a function of the never-exceed speed and wing loading.
What types of synthetic fibers are used for covering aircraft?
Fiberglass and heat-shrinkable polyester fibers.
Which of the several types of fabric is unaffected by moisture and mildew?
What is the function or purpose of reinforcing tape?
Reinforcing tape is used between the fabric and the rib stitching to prevent the lacing cord from cutting through the fabric.
Where would you use surface tape?
Over rib stitching and sewed seams, over lapped edges, around comers, and along leading and trailing edges.
How should the edges of drainage, inspection, and ventilation holes be reinforced?
With plastic, aluminum, or brass grommets.
What are the principle methods used to test the condition of fabric?
Punch testers such as the Maule or Seybolt tester, and laboratory pull-testing.
Fabric is considered unairworthy when it has deteriorated to what percentage of its original strength?
Less than 70%.
How should a structure that will be covered with doped fabric be prepared following inspection and prior to covering?
Treat it with a protective coating of paint or varnish as appropriate.
What is the principal advantage of the envelope method for covering wings?
Almost all the seams are machine-sewed by the envelope supplier.
What is a tie-off knot?
A standard, modified seine knot used on all stitches except the starting stitch.
Name three common types of machine-sewed seams.
Plain overlap, folded-fell, and French-fell.
Where are anti-tear strips used?
Under wing rib stitching when the never-exceed speed is greater than 250 mph.
How would you determine the correct spacing for rib stitching if the original spacing was unknown?
Consult the chart in AC 43.13-1B.