*
Motive flow check valve
*
Vapor vent valve
*
Inlet valve.
The discharge check valve prevents engine feed manifold fuel from flowing back through the pump.
The motive flow check valve prevents fuel from the scavenge pumps from flowing back through the pump.
EFFECTIVITY
BEJ ALL
The vapor vent valve permits fuel vapor to go into the tank, but does not permit fuel to enter the pump.
The inlet valve is a gate valve that closes when you remove the pump. This permits you to remove the pump when the tanks have fuel in them.
Motor-Impeller
The motor-impeller uses 115v ac power. Each pump has these parts:
*
Electrical connector
*
Pressure switch
*
Drain plug
*
Extraction lever.
Training Information Point
The override/jettison pump motor-impellers are interchangeable with the jettison pump motor-impellers.
To remove the motor-impeller, you rotate it 35 degrees CCW to close the inlet valve. Then you remove the drain plug to remove residual fuel. You use the extraction lever to move the motor-impeller out of the housing.
To install the motor-impeller, you must align pins in the housing to slots on the motor-impeller.
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ENGINE FUEL FEED -OVERRIDE/JETTISON PUMP
You can remove the discharge, motive flow, and vapor vent valves through the housing from outside the tank.
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ENGINE FUEL FEED -OVERRIDE/JETTISON PUMP
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D633W101-BEJ Sep 05/2002
ENGINE FUEL FEED -CENTER TANK FUEL SCAVENGE JET PUMP
Purpose
The fuel scavenge jet pumps take fuel from the low points in the center tank and send it to the main tanks. This increases the amount of usable fuel in the center tank. Float-operated shutoff valves prevent fuel scavenge when the main tanks are full.
Location
There is one fuel scavenge jet pump in each side of the center tank. They are in the left and right wheel wells on the rear spar.
There is an outlet float-operated shutoff valve in each main tank. You get access to these valves through the fourth fuel tank access door.
There is an inlet float-operated shutoff valve in each side of the center tank. You get access to these valves through the first fuel tank access door.
Functional Description
The jet pumps operate automatically when the boost pumps are on. They use fuel from the boost pumps as motive fuel. The flow of the motive fuel through the jet pump causes suction that takes fuel from the center tanks. The fuel goes through the jet pump discharge lines to the main tanks. When the main tanks are full, the outlet float-operated shutoff valve closes to stop fuel flow through the discharge line.
The inlet float-operated shutoff valve prevents motive flow to the jet pump until the center tank is almost empty. This prevents the fuel from flowing into the main tank too early if the outlet float-operated shutoff valve fails. A check valve in the jet pump prevents fuel movement from the main tank to the center tank.
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ENGINE FUEL FEED -CENTER TANK FUEL SCAVENGE JET PUMP
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777 AIRCRAFT MAINTENANCE MANUAL
THIS PAGE IS INTENTIONALLY LEFT BLANK
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ENGINE FUEL FEED -BOOST PUMP
General
The boost pumps supply main tank fuel to the engine feed manifold.
The boost pumps can supply fuel at a pressure of 12 psi and a flow rate of 35,200 pounds (16,000 kgs) per hour. Each pump assembly has a motor-impeller and a housing.
Location
There are two boost pumps in each main tank. The forward boost pumps are on the rear spar, outboard of each main landing gear shock strut. The aft boost pumps are on the rear spar, inboard of each main landing gear shock strut. The housings are inside the tanks, on the rear spar. The motor/ impellers install in the housings.
Pump Housing
The housing contains the motor-impeller and these valves:
*
Discharge check valve
*
Motive flow check valve
*
Vapor vent valve
*
Inlet valve.
The discharge check valve prevents engine feed manifold fuel from flowing back through the pump.
EFFECTIVITY
BEJ ALL
The motive flow check valve prevents fuel from the scavenge pumps from flowing back through the pump. 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 飛行操縱 Fuel(13)
