Aircraft Fabric Covering

Question 1

Aircraft covering fabrics are made of materials from what two sources?

Answer 1

Organic materials and synthetic materials.

Question 2

How would you determine the strength requirements for fabric used to recover an aircraft?

Answer 2

The fabric must be of at least the quality and strength of the fabric used by the original manufacturer.

Question 3

What two types of organic fibers are used for covering aircraft?

Answer 3

Cotton and Linen.

Question 4

What is meant by warp, weft, and bias?

Answer 4

Warp is the direction along the length of the fabric, weft is the direction across the fabric at right angles to the warp, and bias is a direction at a 45 degree angle to the warp and well.

Question 5

What is the purpose of the selvage edge on a roll of fabric?

Answer 5

It prevents the fabric from unraveling.

Question 6

What identification marking is found on the selvage edge, and in which direction is the warp
applied?

Answer 6

The FAA-PMA stamp is found on the selvage edge and the warp is applied parallel to the line of flight.

Question 7

How are the fabric type and strength requirements determined for fabric-covered aircraft?

Answer 7

The original manufacturer determines the fabric type, and the strength requirements are a function of the never-exceed speed and wing loading.

Question 8

What types of synthetic fibers are used for covering aircraft?

Answer 8

Fiberglass and heat-shrinkable polyester fibers.

Question 9

Which of the several types of fabric is unaffected by moisture and mildew?

Answer 9

Fiberglass.

Question 10

What is the function or purpose of reinforcing tape?

Answer 10

Reinforcing tape is used between the fabric and the rib stitching to prevent the lacing cord from cutting through the fabric.

Question 11

Where would you use surface tape?

Answer 11

Over rib stitching and sewed seams, over lapped edges, around corners, and along leading and trailing edges.

Question 12

How should the edges of drainage, inspection, and ventilation holes be reinforced?

Answer 12

With plastic, aluminum, or brass grommets.

Question 13

What are the principle methods used to test the condition of fabric?

Answer 13

Punch testers such as the Maule or Seybolt tester, and laboratory pull-testing.

Question 14

Fabric is considered unairworthy when it has deteriorated to what percentage of its original strength?

Answer 14

Less than 70%.

Question 15

How should a structure that will be covered with doped fabric be prepared following inspection and prior to covering?

Answer 15

Treat it with a protective coating of paint or varnish as appropriate.

Question 16

What is the principal advantage of the envelope method for covering wings?

Answer 16

Almost all the seams are machine-sewed by the envelope supplier.

Question 17

What is a tie-off knot?

Answer 17

A standard, modified seine knot used on all stitches except the starting stitch.

Question 18

Name three common types of machine-sewed seams.

Answer 18

Plain overlap, folded-fell, and French-fell.

Question 19

Where are anti-tear strips used?

Answer 19

Under wing rib stitching when the never-exceed speed is greater than 250 mph.

Question 20

How would you determine the correct spacing for rib stitching if the original spacing was un-known?

Answer 20

Consult the chart in AC 43.13-1B.