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49-27-00
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
OIL FILTER SEE C SEE B
A
SEE A
CHIP DETECTOR PORT FOR THE ACCESSORY GEARBOX
APU FUEL LINE
CHIP DETECTOR HOUSING
MAGNETIC PLUG
CHIP DETECTOR PORT FOR THE MAGNETIC PLUG APU DRAINS
ACCESSORY CHIP
GEARBOX DETECTOR
HOUSING
B C
APU Oil Filter and Magnetic Plug and Chip Detector Component Location
Figure 1
F58296
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
G00600
NO. 1 NO. 2 NO. 3 NO. 4
ACOC
THERMAL/PRESSURE
BEARING BEARING BEARING BEARING
BYPASS VALVE
OIL
TANK
ANTI SYPHON
SCREEN
NO. 0 BEARING
LGB
CHIP
DETECTOR
SCREEN SCREEN SCREEN
DIST
BLOCK
AGB SCREENCOLD START
CHIP DETECTOR
~P INDICATOR
VALVE CHECKVALVE
P
R
FCOC V PRESS. PUMP FILTER THERMAL/PRESSURE PRESS
PT
SENSE LINE BYPASS
VALVE PRESSURE OIL
SCAVENGE OIL
LGB. SCAV. PUMP
BYPASS OIL
AGB. SCAV. PUMP
A
747-400
MAINTENANCE MANUAL
APU Lubricating System Schematic
Figure 2
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
NO. 4 BRG. PUMP
A
747-400
MAINTENANCE MANUAL
(4)
Pressure oil into the load gearbox flows into an oil gallery and provides lubrication for the load gearbox by a combination of jets and oil mist. The two generator drives incorporate oil lubricated output splines. The cooling fan drive oil nozzle routes oil from the load gearbox to the bearings via the cooling fan gearshaft. An internal passage is utilized to supply under race lubrication for the No. 0 bearing. The pressurized oil for No. 0 bearing flows through a screen which protects the bearing from foreign matter.
(5)
Oil is also routed from the load gearbox gallery to a transfer block on the oil filter housing. An internal passage located between the oil filter housing and the accessory gearbox routes pressurized oil to lubricate the accessory gearbox. Both No. 1 and 2 bearings are under race lubricated from jets located in the carbon seal support housing. Oil is supplied to the support housing through internal passages.
(6)
Oil to lubricate No. 3 and No. 4 bearing flows from the transfer block, through an external tube to a boss located on the gas generator case. Oil to lubricate the No. 3 bearing flows from the boss through internal tubing, to oil jets in the bearing cavity. An inlet screen in the oil feed upstream of the bearing protects the bearing from foreign matter. An oil pressure feed tube to supply oil for No. 4 bearing lubrication is routed from the boss,through struts supporting the exhaust duct. A jet, at the rear of the bearing cavity and integral with the exhaust casing, provides the oil for under-race lubrication of No. 4 bearing. A screen in the oil feed line upstream of the bearing oil nozzle prohibits foreign matter from entering the No. 4 bearing cavity.
B.
Scavenge Oil System
(1)
The scavenge oil system returns used oil to the oil tank. Oil from the cooling fan is gravity drained, through an external transfer tube, into the load gearbox. Scavenge oil from No. 0 bearing is also gravity drained to the load gearbox through a passage at the bottom of the bearing cavity. Oil in the load gearbox is gravity drained into a sump at the bottom of the housing. From the sump, the load gearbox scavenge pump returns the oil through the external scavenge oil tube to the oil tank. A magnetic chip detector, installed at the bottom of the gearbox housing, collects any ferrous metal particles in the oil to give an indication of APU condition.
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