SEALING - GENERAL - DESCRIPTION AND OPERATION

** ON A/C NOT FOR ALL

1. General
This topic gives data about the reasons for the use of sealants on the aircraft and the primary sealing areas.
For sealing repairs (Ref. AMM 51-76-00).

** ON A/C NOT FOR ALL

2. Description

Areas of Sealing

A. Use of Sealants

(1) The primary uses for sealants on the aircraft are:

sealing the fuselage structure to make sure that the necessary internal pressure is kept during the flight,
sealing the fuel tanks (Ref. AMM 51-76-12 for the repair of fuel tank sealing),
sealing the external joints of the aircraft structure to make sure that water does not go into the structure and to make the structure smoother,
sealing riveted and bolted joints to make sure that liquids do not get into the joints,
sealing sandwich structures to make sure that moisture does not go into the structure,
to prevent corrosion (galvanic action) between different metals,
to prevent corrosion between different materials, especially between CFRP and aluminum alloys,
to prevent fretting corrosion (fatigue stress or vibration between parts of the structure can cause this),
to fill cavities,
to protect the surface on housings, channels, tubes, electrical cables and electrical components,
where it is necessary to make sure that any leakage of the aircraft fluids is kept in the areas from which you can drain them, for example, under the galleys and lavatories.
Areas of Sealing

B. Sealed Areas

(1) The aircraft is divided into three primary areas for sealing:

(a) The pressurized area of the fuselage which is from STA350(FR1) to STA3365(FR70). It includes the cockpit, the cabin and the cargo compartments.

(b) The nonpressurized areas of the aircraft which include:

the MLG and NLG bay,
the wing center box,
the airconditioning and hydraulic compartments,
the tail section of the rear fuselage aft of FR70,
the vertical and horizontal stabilizers,
the wings.

[Rev.10 from 2021] 2026.04.01 01:34:19 UTC