B. Closing the FUEL FLOW circuit breaker on the FUEL SYSTEM circuit breaker panel P6 provides 115-volt ac power to the fuel flow power supply. The power supply furnishes an 8-cycle electrical output that drives the fuel flow transmitter. The transmitter measures the mass of fuel flow and produces an output signal to the flow rate/fuel consumed indicator. The transmitter output signal is proportional to fuel flow.
C. The electrical signal received by the flow rate/fuel consumed indicator causes the fuel flow dial indicator and the fuel consumed digital readout counter to rotate. The 115-volt ac power, received by the flow rate/fuel consumed indicator, flows to ground when the fuel flow reset switch is open. Closing the fuel flow reset switch allows power to energize a relay which causes the fuel consumed digital readout counter to return to zero. (See figure 2.)
H59260
Fuel Flow Indicating System Block Diagram 529
73-31-01 Figure 2 Feb 15/71
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Jun 20/91 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 73-31-01 Page 101
CONTINUED FROM PRECEDING PAGE
B
OK - With interchanged indicator, replace old indicator.
NOT OK - Repair wiring and wrap chaffed area with Teflon tape.
503
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
A B
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FUEL FLOW TRANSMITTER - REMOVAL/INSTALLATION
EFFECTIVITY
AH 7T-VEC BO N21SW and N22SW EF ALL EXCEPT B-2607 FL ALL EXCEPT N7340F, N7341F and N7384F GJ ALL EXCEPT B-2509 and B-2510 VM ALL EXCEPT 737-2K9 Airplanes
1. General
A. Removal/Installation procedures for any one of the fuel flow transmitters are basically the same, the only difference being one of location. There is one transmitter mounted on the forward left side of each engine.
2. Prepare to Remove Fuel Flow Transmitter
A. Pull applicable fire switch to close engine fuel shutoff valve. Pull applicable ENG SHUTOFF VALVE circuit breaker on circuit breaker panel P6.
NOTE: Engine fuel shutoff valves may be closed manually if desired.
B. Pull both FUEL FLOW circuit breakers on circuit breaker panel P6.
CAUTION: FUEL FLOW CIRCUIT BREAKER MUST BE OPENED PRIOR TO DISCONNECTING TRANSMITTER CONNECTOR. FAILURE TO DO SO CAN RESULT IN DAMAGE TO INDICATOR RESET MECHANISM. DAMAGE WILL RESULT IF RESET BUTTON IS PUSHED OR BY PICKUP OF STRAY SIGNALS IF INDICATOR IS ENERGIZED AND THE TRANSMITTER IS DISCONNECTED.
C. Open left side cowl panel on applicable engine.
3. Remove Fuel Flow Transmitter
A. Place suitable container under transmitter to catch fuel spillage.
B. Disconnect electrical connectors from transmitter (Fig. 401).
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