Non-Metalics III

What is used as a protective finish for the inside of steel tubing?

Hot linseed oil.

What is used to slow the drying time of some finishes to prevent blushing?

Retarder.

Why is the surface tape used on the trailing edge of the control surfaces of some airplanes notched?

Since the edges of this tape face into the wind, it is possible that it could start to lift and form a very effective spoiler. If the tape is notched, it will tear off at a notch.

What can be done to remedy blushing that has formed on a doped surface that has just been sprayed?

Spray a very light mist coat of a mixture of one part retarder to two parts of thinner over the blushed area. Allow it to dry and spray on another coat. If this is does not remove the blush, the blushed dope will have to be sanded off and a new coat applied.

Which of the following is a hazard associated with sanding on fabric covered surfaces during the finishing process?

Static electricity buildup.

What is the preferred seam used for machine-sewing pieces of aircraft fabric together?

The French fell seam.

When mixing epoxy paint, should the converter be added to the resin or the resin to the converter?

The converter should always be added to the resin never the resin to the converter.

What paperwork must be completed for an aircraft that was originally covered with Grade A cotton fabric is re-covered with synthetic fabric?

The covering must be done according to the Supplemental Type Certificate, and a Form 337 must be executed, stating that all materials and processes complied with the requirements of the STC.

What happens to an enamel finish when paint remover is applied to it?

The enamel softens and swells so that it pulls away from the surface of the metal.

What is the usual cause of runs and sags in aircraft finishes?

Too much material applied in one coat.

What is the general reason for runs and sags in a finish that is being sprayed onto a flat surface?

Too much paint is being applied. The film is too thick.

Machine-sewn seams in aircraft covering fabrics may be of the folded-fell or French-fell types.

True.

Which type of coating typically includes phosphoric acid as one of its components at the time of application?

Wash primer.

What type of rib lacing cord is recommended for attaching cotton fabric to an aircraft structure?

Wax linen cord.

A correct use of acetone is to?

remove grease from fabric.

If registration numbers are to be applied to an aircraft with a letter height of 12 inches, what is the minimum space required for the registration mark N1686C?

52 inches.

When testing the strength of Grade A cotton fabric covering an aircraft that requires only intermediate grade, the minimum acceptable strength that fabric must have is?

70% of the original strength for intermediate fabric.

What type of hand-sewing stitch is used when sewing in a panel of new fabric on an aircraft fabric covered wing?

A baseball stitch, locked every eight to ten stitches.

What is likely to occur if hydrated wash primer is applied to unpainted aluminum and then about 30 to 40 minuets later a finish topcoat, when the humidity is low?

A glossy, blue-free finish.

What type of knot is used for locking the stitches that are used for rib lacing on a fabric-covered aircraft wing?

A modified seine knot.

When is the finishing tape applied to a fabric covered wing when it is being recovered?

After the second coat of dope has dried and the nap of the fabric has been sanded off.

When dope-proofing the parts of the aircraft structure that come in contact with doped fabric, what provides an acceptable protective coating?

Aluminum foil and cellulose tape.

What is the anitear strip, and when are they required on a fabric-covered aircraft?

An antitear strip is a strip of the same type of fabric as is used for covering the wings. It is laid over the rib between the reinforcing tape and the fabric. An antitear strip is required for the aircraft that have a never-exceed speed in excess of 250 miles per hour.

How is the strength of the fabric on an aircraft structure determined?

An approximate strength test can be made with FAA-approved fabric punch tester, but the only way to know for sure that the fabric has sufficient strength is by pull-testing a one-inch-wide sample of the fabric.

Where are the drainage grommets located on a fabric covered aircraft wing?

At the lowest point in each bay.It is customary to install a grommet on each side of a wing rib on the underside of the wing, at the trailing edge.

Which defect in aircraft finishes may be caused by adverse humidity, drafts, or sudden changes in temperature?

Blushing.

Should a sewed seam in the fabric used to cover an aircraft wing run spanwise or chrodwise?

Both spanwise and chordwise seams are permissible, but chordwise seams are preferred.

What is likely to occur if unhydrated wash primer is applied to unpainted aluminum and then about 30 to 40 minutes later a finish topcoat, when the humidity is low?

Corrosion.

What are three types fabric that can be used to cover an aircraft?

Cotton fabric, synthetic fabric, and glass fabric.

What type of material is used for inter-rib bracing in a fabric-covered aircraft wing?

Cotton reinforcing tape.

If masking tape is applied to an aircraft such as for trim spraying, and is left on for several days and/or exposed to heat, it is likely that the tape will?

Cure to the finish and be very difficult to remove/

Why are some portions of the structure of an aircraft dope proofed before they are covered with fabric?

Dope proofing keeps the fabric from sticking to the structure when the first coat of dope is applied. The fabric normally sags enough to touch the structure before it begins to pull taut.

When and how is finishing tape applied on a fabric covered aircraft?

Doped on after the first or second coat of dope.

What is the minimum strength to which aircraft fabric is allowed to deteriorate before it is considered to be unairworthy?

Fabric can deteriorate to 70% of the strength of the fabric that is required for the aircraft.

How many fabric thicknesses will be found in a French-fell seam?

Four

What is the recommended type of repair to a fabric covered aircraft surface when it has an L-shaped tear with each f the legs of the tear more than 14 inches long?

If the never exceed speed of the aircraft is less than 150 miles per hour, a doped-on repair patch can be made.

How is polyester synthetic fabric shrunk on an aircraft structrure?

It is shrunk with heat from an iron or from a heated blower.

How thick should a coat of wash primer be that is used on an aluminum alloy aircraft structure?

Its should be thin enough that it does not hide the surface of the metal.

What are the two basic types of dope that are used on fabric-covered aircraft?

Nitrate dope and butyrate (CAB) dope.

What kind of dope is used on polyester synthetic fabric that has been heat-shrunk on an aircraft structrure?

Nontautenting butyrate dope.

Which statement is true regarding paint system compatibilty?

Old wash primer coats may be overcoated directly with epoxy finishes.

How can a vinyl film decal be removed from an aluminum alloy surface?

Place a cloth saturated with cyclohexanone or MEK over the decal until it is softened, and scrape it off of the surface with a plastic scraper.

Which properly applied finish topcoat is the most durable and chemical resistant?

Polyurethane.

Fabric rejuvenator is used to?

Restore the condition of dope coatings.

How is the finish removed from a fiberglass aircraft component that is being repaired?

The finish must be sanded off. Paint remover can soften the resin of which the component is made.

What is done to cotton and linen fabric to protect it from mildew?

The first coat of dope that is used on cotton and linen fabric has a mildewicide mixed in it.

What safety precaution must be observed when sweeping a paint room that has dried dope or lacquer overspray on the floor?

The floor must be wet down with water before it is swept. Static electricity from dry sweeping can cause a fire.

What determines the spacing of the rib lacing stitches on a fabric-covered aircraft wing?

The never-exceed speed of the aircraft.

What is the purpose of the reinforcing tape that is used between the fabric and the rib lacing on an aircraft wing?

The reinforcing tape keeps the rib lacing cord pulling through the fabric.

Why is retarder used in dope when the dope is being sprayed in humid conditions?

The retarder slows the drying of the dope and keeps it from blushing.

What should be done to an aircraft surface that is covered with paint remover to give the remover the maximum amount of time to soak into the old finish?

The surface should be covered with a piece of polyethlene sheeting such as a paint drop cloth. This will keep the solvents from evaporating before they have time to penetrate the paint film.

What will happen if dope is sprayed over an enameled surface?

The thinner in the dope will penetrate the enamel surface and causes it to swell.

Why should wooden wing spars be finished with a transparent varnish?

The transparent finish allows any decay or rot that develops in the wood to be detected.

When are drainage grommets applied when an aircraft is being re-covered?

They are laid into the third coat of dope, at the same time the surface tape is applied.

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

Three inches wide

Finishing tape (surface tape) is used for what purpose?

To provide additional wear resistance over the edges of fabric forming structures.

What type of thinner is used with zinc chromate primer?

Toluol or toluene.

When an aircraft is being re-covered, when is fungicidal dope applied to the fabric?

With the first coat of dope that is brushed into the fabric.

What are the three types of primer that may be used when painting an aircraft?

Zinc chromate primer, wash primer, and epoxy primer.

Before applying a protective coating to any unpainted clean aluminum, you should?

avoid touching the surface with bare hands.

Fungicide and mildewicide additives are important for fabric covered aircraft, such as?

cotton and linen.

Fungicidal dopes are used in aircraft finishing as the?

first coat to prevent fabric rotting and are applied thin enough to saturate the fabric.

Moisture, mildew, chemicals, and acids have no effect on?

glass fabric.

Aluminum-pigment in dope is used primarily to?

reflect ultraviolet from the fabric.

The best method of repair for a fabric-covered surface which has an L-shaped tear, each leg of which is approximately 14 inches long is to?

sew with a baseball stitch from the center of the tear out toward the extremity of each leg and the dope on a patch.

The determining factor(s) of the selection of the correct weight of textile fabric to be used in covering any type of aircraft is the?

speed of the aircraft and the maximum wing loading.

The strength classification of fabrics used in aircraft covering is based on?

tensile strength.