Kinds of Sealants

This section discusses the three kinds of sealants in general use in

Army aviation and sealant repair. The information in this section is

important because some areas of an airframe structure are sealed

compartments used for fuel tanks and others are for crew and

passenger use.

Fuel tank compartments are tightly sealed to keep

fuel vapors from coming into the aircraft's interior.

Crew and

passenger compartments are sealed tightly to permit controlled

ventilation. Because it is not possible to seal these areas tightly

enough with only a riveted joint, a sealing compound is used.

Sealants are also used to add aerodynamic smoothness to such exposed

surfaces as seams and joints in the fuselage and wings.

KINDS OF SEALANTS

Rubber, sealing compound, and special seals are the three kinds of

sealants generally used in Army aviation.

The applicable technical

manual for the aircraft being worked on must be consulted for details

on sealer application. The paragraphs that follow describe each kind.

Rubber Seals. Rubber seals are used at all points where the seal

is broken frequently for necessary repairs.

Examples of such

locations are canopies and access doors.

Because the seal must be

continuous around the joint, it cannot be repaired.

Therefore,

anytime a rubber seal is damaged or broken for repairs, it must be

replaced.

Sealing Compounds. Sealing compounds are used at points where the

seal is seldom broken except for structural maintenance or part

replacement, as with riveted lap and butt seams and joints. They can

also be used to fill gaps or holes up to 1/16 inch in width.

Special Seals. Special seals are required to pass cables, tubing,

mechanical linkages, and wires into and out of sealed areas.

Wires

and tubing are passed through sealed-area bulkheads by using such

bulkhead fittings as cannon plugs for wiring and couplings for

tubing. These fittings are sealed to the bulkhead, and the wires and

tubes are fastened to them from each side.

All seals of moving

components, such as flight controls, are subject to wear. Therefore,

care must be taken when they are installed, and they must be

inspected regularly.

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SEALANT REPAIR

All surfaces that are to be sealed must be thoroughly cleaned to

ensure maximum adhesion between the surface and the sealant.

Only

approved strippers, cleaners, and sealants can be used; and, even

though approved, the stripper compound must be used with care.

Details on cleaning and the sealant to be used can be found in the