FUEL JETTISON -COMPONENT LOCATIONS -WINGS

General
There is a jettison nozzle on each wing. The nozzles are on the wing trailing edges, near the ailerons.
There is a jettison nozzle valve and actuator on each wing. Each nozzle valve is in the dry bays near the surge tanks. The valve attaches to the refuel/jettison manifold.
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FUEL JETTISON -COMPONENT LOCATIONS -WINGS

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FUEL JETTISON -FUEL JETTISON PUMP

General
The jettison pumps supply fuel from the main tank to the refuel/ jettison manifold during fuel jettison.
The jettison pumps can supply fuel at a pressure of 36 psi and a flow rate of 70,000 pounds (31750 kg) per hour. Each pump assembly has a motor-impeller and a housing.
Location
There is one jettison pump in each main tank. They are on the rear spar, aft of the engine 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

*
Vapor vent valve

*
Inlet valve.

The discharge check valve prevents engine feed manifold fuel from flowing back through the pump.
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 jettison pump motor-impellers are interchangeable with the override/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.
You can remove the discharge and vapor vent valves through the housing from outside the tank.
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777 AIRCRAFT MAINTENANCE MANUAL

FUEL JETTISON -FUEL JETTISON PUMP

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FUEL JETTISON -ISOLATION VALVE

Purpose
The fuel jettison isolation valves open during fuel jettison operation. The open isolation valve lets override/jettison pump fuel go to the refuel/jettison manifold.
Location
There is one fuel jettison isolation valve in each section of the center tank. The valve actuators are on the rear spar in the wheel wells.
Isolation Valve Description
The fuel jettison isolation valve is the same type of valve as the other motor-actuated valves in the fuel system.
Actuator
The actuator is a 28v dc motor. It has a manual override lever so you can operate the actuator without electrical power. The lever also shows valve position.
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777 AIRCRAFT MAINTENANCE MANUAL

FUEL JETTISON -ISOLATION VALVE

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FUEL JETTISON -JETTISON NOZZLE VALVE

Purpose
The fuel jettison nozzle valves open during fuel jettison operation. When the valve opens, fuel goes out of the jettison nozzle near the wing tip.
Location
There is one fuel jettison nozzle valve at each end of the refuel/ jettison manifold. They are outboard of the surge tank (outboard of rib 34).
Jettison Valve Description
The fuel jettison nozzle valves are the same type of valve as the other motor-actuated valves in the fuel system.
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777 AIRCRAFT MAINTENANCE MANUAL

FUEL JETTISON -JETTISON NOZZLE VALVE

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FUEL JETTISON -FUNCTIONAL DESCRIPTION -FUEL FLOW

General
Jettison can occur from the center tank or the main tanks. Fuel from the tank flows through the refuel/jettison manifold.
　
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