BYPASS FUEL FROM THE FMULOW POWER MODE
FUEL BYPASS VALVE FLOW SCHEMATIC F
Fuel Distribution System Component Location
Figure 1 (Sheet 4)
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73-11-00
ALL ú ú N01 Page 5 ú Feb 10/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / PW4000 SERIES /747-400 / ENGINES/MAINTENANCE MANUAL ////////////////////////
C. The fuel distribution valve includes a shutoff piston, eight fuel outlet valves, and a 73 micron cleanable strainer which has a bypass function.
(1)
With the engine stopped, the distribution valve piston does not let fuel go into the fuel manifolds.
(2)
During the engine start, fuel flow goes to the eight fuel manifolds when the fuel pressure to the distribution valve is 20 psi (140 kPa). At this pressure, the piston moves back and lets go fuel into the fuel manifolds.
(3)
During the engine shutdown, the piston moves back when fuel pressure decreases to stop fuel flow. As the piston moves back, it lets six drain ports drain fuel from six fuel manifolds. Two fuel manifolds stay full of fuel for faster engine starts.
5. Fuel Injector and Supports (Fig. 1)
__________________________
A. Twenty-four fuel injectors are installed around the diffuser case. Eight fuel manifolds supply fuel to the fuel injectors. Each manifold supplies fuel to three fuel injectors.
B. The fuel injectors are single-orifice, moderate fuel pressure decrease, aerating fuel nozzles. The fuel injectors use air velocity to atomize the fuel. Each fuel injector will permit a fuel flow of 15-1000 pph (6.80-453.60 kgph) with a 70 degree spray cone angle.
C. Each fuel injector has a removable inlet screen.
6. Operation
_________
A. Fuel is supplied to the fuel pump by fuel boost pumps (Ref 28-22-00) through the fuel supply line.
B. The fuel is pressurized to 90-210 psi (620-1450 kPa) (intermediate stage pressure) by the fuel pump boost stage. The fuel, at intermediate stage pressure, is sent through the fuel/oil cooler. This increases the temperature of the the fuel to remove ice in the fuel and decreases the temperature of the the IDG and engine oil.
C. The fuel goes back to the fuel pump from the fuel/oil cooler and flows through the fuel pump filter.
D. Filtered fuel goes into the main stage of the fuel pump where it is pressurized to 450-900 psi (3100-6200 kPa) (main stage pressure). The fuel at main stage pressure flows through the fuel metering unit (AMM 73-21-00). The fuel metering unit sends a metered quantity of fuel to the fuel distribution valve and sends the fuel which is not used to the fuel bypass valve.
E. The bypass valve sends fuel, bypassed from the fuel control, through the fuel/oil coolers for the IDG and engine at low speed, or through just the fuel/oil cooler for the engine at high speeds.
F. Metered fuel, from the fuel control, goes to the fuel distribution valve, where it goes to each of the eight fuel manifolds. Fuel from the fuel manifolds goes into the fuel injectors, where it goes into the engine combustion chamber.
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73-11-00
ALL ú ú N01 Page 6 ú Jun 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
FUEL DISTRIBUTION SYSTEM - INSPECTION/CHECK
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1. General
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A. This procedure gives the tasks to examine the fuel tubes for clearance and damage (par.2), and to examine the fuel distribution system for leaks (par.3). This inspection gives the steps to examine the fuel distribution system from the fuel distribution valve to the fuel injectors.
TASK 73-11-00-206-001-N00
2. Fuel Tube Inspection
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A. References
(1)
AMM 71-11-04/201, Fan Cowl Panels
(2)
AMM 71-11-06/201, Core Cowl Panels
(3)
AMM 78-31-00/201, Thrust Reverser System
B.
Access
(1)
Location Zone 412 Engine 1 - HPC Case lower half, Diffuser/Combustor Case 422 Engine 2 - HPC Case lower half, Diffuser/Combustor Case 432 Engine 3 - HPC Case lower half, Diffuser/Combustor Case 442 Engine 4 - HPC Case lower half, Diffuser/Combustor Case
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