The upper bulb-seal fire seals are mounted in retainer tracks on the inner surface of the upper bifurcation wall and aft cowl. These fire seals contact seal depressors mounted on the strut.
The lower bulb-seal are mounted in retainer tracks on the inner surface of the lower bifurcation wall. These fire seals contact seal depressors mounted on the engine drain mast.
Physical Description
The rubber fire seals are constructed from a silicone rubber that is reinforced with fabric layers. The rubber fire seals are bulb-seals that have a circular cross-section and foot that fits in a metal seal retainer track. The bulb-seals can be hollow or can be filled in some segments with a sponge foam to prevent collapse of the seal where the seal changes direction. The rubber fire seals are also molded into specific shapes for some areas.
Training Information Point
You must open the thrust reverser to get access to the fire seals.
When the thrust reverser is closed and latched, the bulb-type fire seals are flattened when pressed against the seal depressors. There is a minimum seal contact width along the length of the fire seal for correct installation. Bulb-type fire seals that are damaged or missing are replaced.
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PW4000 SERIES ENGINES
777 AIRCRAFT MAINTENANCE MANUAL
Thrust Reverser Fire Seals
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THRUST REVERSER SYSTEM -THERMAL INSULATION BLANKETS
General
The inside wall of the thrust reverser is covered with thermal insulation blankets.
Purpose
The blankets are a thermal insulation and fire barrier layer which is necessary to keep the thrust reverser structurally serviceable and can decrease the damage and repair costs from a duct burst or a fire. The thermal insulation in the blanket protects the composite inner wall of the fan duct cowl from heat damage from fires and engine operation.
Location
The blankets are installed on the upper bifurcation of the thrust reverser next to the fire seal, on the inside surface of the thrust reverser inner wall, aft of the vertical fire seals, and on the lower bifurcation down to the thrust reverser latch beam. For aft cowls with an waffle-grid structure, blankets are also installed on the aft cowl next to the tension latch housings and the forward and aft frames that contain the deflection limiter tension straps. For aft cowls with conventional skin and stringer construction, no blankets are installed on the aft cowl. 中國航空網 www.k6050.com 航空翻譯 www.aviation.cn 本文鏈接地址：777 AMM 飛機維護手冊 發動機排氣 Engine Exhaust PW 777 AIRCRAFT MAINTENANCE MANUAL(22)
