Aircraft Covering

Question 1

What determines the required quality and strength of fabric that is to be used for covering aircraft?

Answer 1

The original manufacturer by the never-exceed airspeed and wing loading.

Question 2

When are anti-tear strips recommended and where are they used?

Answer 2

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 all areas in the slipstream.

Question 3

What is the maximum permissible deterioration of aircraft fabric before it is considered unairworthy?

Answer 3

30 percent of the original fabric strength.

Question 4

What should be the strength of the fabric used for re-covering an aircraft?

Answer 4

All fabric, surface tape, reinforcing tape, thread and lacing cord used to re-cover or repair an aircraft
covering 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.

Question 5

What is the purpose and location of drain grommets in aircraft fabric?

Answer 5

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 at the lowest point along the center of the underside of each fuselage bay.

Question 6

How are drain grommets installed in aircraft fabric?

Answer 6

Brass grommets should be mounted on fabric patches and then doped to the covering. Plastic low Foot
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.

Question 7

Name the methods of applying fabric to an aircraft wing.

Answer 7

Blanket and envelope method.

Question 8

What is the purpose of reinforcing tape?

Answer 8

Reinforcing tape is used under all stitching and prevents the stitching cord from tearing through the fabric.

Question 9

What type of fabric is not affected by moisture or mildew?

Answer 9

Fiberglass fabric is not affected by moisture, mildew, chemicals, and most acids.

Question 10

What methods are used to check the strength or the condition of doped fabric?

Answer 10

A test strip, punch tester, or when results are marginal, a laboratory test is needed.

Question 11

What type of machine-sewed seems are used in aircraft covering?

Answer 11

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

Question 12

What should be done with structure that will come in contact with doped fabric?

Answer 12

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, or cellulose tape.

Question 13

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?

Answer 13

Use the rib stitch spacing chart in the AC 43.13-18

Question 14

What is the standard tie-off knot used during rib stitching?

Answer 14

A modified seine knot is used to tie off all stitches except the starting stitch.

Question 15

What do you call the edge of cloth, tape, or webbing that has been woven to prevent raveling?

Answer 15

Selvage edge.

Question 16

The type of fabric used for covering aircraft.

Answer 16

The organic fibers are cotton and linen. The synthetic fibers include fiber glass and heat shrinkable
synthetic fibers such as nylon and Dacron. { Organic and polyester (synthetic)}.

Question 17

When covering aircraft, where is surface tape used?

Answer 17

Sewed seams, tapped edges, and all stitching is covered with surface tape. The surface tape has a
pinked-edge to prevent unravelling during the installation process.

Question 18

Name the advantages of using the envelope method to cover fabric aircraft.

Answer 18

It saves labor because practically all sewing is done by machine. It is similar to pulling a sock over
the wing. The only stitching left to do would be to the structure.

Question 19

How are wrinkles removed from cotton fabric?

Answer 19

By wetting the wrinkles and allowing it to dry.

Question 20

When is finishing tape applied?

Answer 20

After the second coat of dope is dry, and the nap has been sanded away.

Question 21

How wide should surface tape be when used to cover the trailing edge of an aircraft wing?

Answer 21

Three inches

Question 22

What is the recommended type of repair for an L-shaped tear when the legs are more than 14 inches long?

Answer 22

A doped on patch, as long as the never-exceed velocity is less than 150 mph.

Question 23

What is the fabric warp?

Answer 23

The direction along the length of fabric.

Question 24

What is the purpose of reinforcing tape?

Answer 24

Most commonly used on rib caps after the fabric covering is installed to protect the area
for attaching the fabric to the ribs.

Question 25

What rib lace spacing is used when the original spacing is unknown?

Answer 25

Use the chart in AC 43.13-1B.

Question 26

What are the organic fibers used for covering aircraft?

Answer 26

Cotton and linen.

Question 27

How are ventilation and drainage hole edges reinforced?

Answer 27

With plastic, or aluminum grommets.

Question 28

What is a fabric selvage edge?

Answer 28

An edge of cloth woven to prevent raveling.