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73-21-16
ALL ú ú N02 Page 405 ú Feb 15/99
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
FUEL FLOW INDICATING SYSTEM - DESCRIPTION AND OPERATION
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1. General
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A. The fuel flow indicating system supplies an indication, in the flight compartment, of the rate of fuel which is used.
B. The fuel flow indicating system includes the fuel flow transmitter and uses the auxiliary EICAS for display.
C. Fuel flows through the fuel flow transmitter to the fuel injectors.
2. Fuel Flow Transmitter (Fig. 1)
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A. The fuel flow transmitter is installed to the inlet of the fuel
distribution valve on the HPC case at the 4 o'clock position.
B. The fuel flow transmitter includes a driver assembly (a driver and petal valve), a stationary fuel flow straightener, impeller, drum, restraining spring, coil, shaft, and a housing.
C. The fuel flow transmitter can find fuel flows up to 12,250 kgs/hour. No power supply is necessary for the fuel flow transmitter.
3. Fuel Flow Indication (Fig. 2)
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A. The fuel flow transmitter supplies two signals to the EFIS/EICAS interface units (EIU), which are interpreted and shown on the auxiliary EICAS as fuel flow in kilograms/hour.
4. Operation (Fig. 3 and 4)
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A. Functional Description
(1)
As the fuel goes into the fuel flow transmitter, the fuel flows through angled drive holes on the driver. The fuel flow through the drive holes causes the driver to turn. The rotation of the driver turns the impeller and the drum which are installed on the same shaft.
(2)
The bypass holes in the driver, covered by petal valves, regulate driver speed at high fuel flow rates. If the fuel pressure is more than the pressure necessary to open the petal valves, the petal valves open and the fuel bypasses the driver holes.
(3)
From the driver holes or bypass holes, the fuel goes through the fuel flow straightener which is stationary in relation to the body of the fuel flow transmitter. Any swirl or other disturbances in the fuel flow are removed as the fuel goes through the fuel flow straightener.
(4)
After the fuel goes through the fuel flow straightener, the fuel goes into the impeller/drum section. The drum is rigidly installed on the same shaft as the driver. Therefore, the drum turns at the same rate as the driver. The impeller, however, is installed on bearings and is turned only by the spring, which is installed to the drum.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
73-31-00
ALL ú ú N06 Page 1 ú Oct 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / PW4000 SERIES /747-400 / ENGINES /MAINTENANCE MANUAL ////////////////////////
SEEA
MAIN FUEL SUPPLY HOSE FUEL FLOW
FWD TRANSMITTER MAIN
FUEL
GEARBOX
DISTRIBUTION
VALVE
A
Fuel Flow Transmitter Location Figure 1
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
73-31-00
ALL ú ú N01 Page 2 ú Jun 10/88
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
SEE A SEE B
78 2N 21 81 1.83 1.62 TAT 1.83 1.62 +21c D-T0 1 REV +23c 1.00 1.83 1.65 AUTOTHROT DISC CABIN ALTITUDE OUTFLOW VLV L
X-BLD EPR (11 LINES)
65 17.6 65 OIL P 17.6 FF 12 0.0 66 18.3 78 TAI 17.6 587 75.6 78 17.6 587 75.6 N 1 EGT FF N 2 21 0.0 81 18.3 535 XB 15 623 15.2 83.7 97 246-324FL 250 KTS PG 1 GEAR DN UPUP DN RECALL SEATBELTS CON IGNITION
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