79-CONTENTS
NGUN Page 4 Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
CHAPTER 79 - OIL
TABLE OF CONTENTS_________________
Subject_______ Chapter SectionSubject_______ Page____ Effectivity___________
SWITCH - PRESSURE, OIL FILTER DIFFERENTIAL Removal/Installation 79-35-01 401 ALL
79-CONTENTS
NGUN Page 5 Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
OIL - DESCRIPTION AND OPERATION
_______________________________
1. General
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A. The engine oil system is a self-contained, recirculating type system, which supplies lubricating oil in specified temperature and pressure limits to the engine main shaft bearings, main and angle gearboxes, and accessory drives.
B. The engine oil system includes the oil storage (79-11-00), distribution (79-21-00), and indicating (79-30-00) subsystems.
C. The indicating system gives the measurements of quantity (79-31-00), pressure (79-32-00), temperature (79-34-00), and filter bypass warning (79-35-00).
2. Operation (Fig. 1)
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A. Oil is supplied from the oil tank to the pressure side of the lubrication and scavenge oil pump and is delivered to the main oil filter. If there is a clogged main oil filter, a bypass valve opens to make sure the oil flow does not stop. A differential pressure switch for the main oil filter detects a pressure decrease across the main oil filter.
B. The filtered, pressurized oil then goes through an air/oil heat exchanger and a fuel/oil cooler to keep the desired oil temperature before distribution to the main shaft bearings and the gearboxes.
C. The air/oil heat exchanger and fuel/oil cooler have bypass valves. If there is an oil core failure in one of the components, the bypass valves will make sure the oil flow does not stop. If the oil temperature is very low (such as during a cold start), the electronic engine control (EEC) operates the bypass valve for the fuel/oil cooler to the open position.
D. The temperature regulated oil then goes through the flow restrictors and last chance strainers (filters) before it goes to the five bearings and the main and angle gearboxes. Bearings No. 1, 1.5, and 2 are in one compartment, while bearings No. 3 and 4 are in different compartments.
E. Scavenge oil is picked up from each bearing compartment and, main and angle gearboxes by the scavenge pumps, and is returned to the oil tank.
F. Breather flow from the No. 1, 1.5, and 2 and No. 3 bearing compartments goes to the main gearbox deoiler, and then bled overboard through a vent in the core cowl panel.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
79-00-00
ALL ú ú N01 Page 1 ú Feb 18/02
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / PW4000 SERIES /747-400 / ENGINES /MAINTENANCE MANUAL ////////////////////////
34
OIL TANK
MAIN GEARBOX
MAIN OIL FILTER
OIL FILTER DIFFERENTIAL PRESSURE SWITCH
INLET PORT
OIL FILTER DIFFERENTIAL PRESSURE SWITCH
OUTLET PORT
LUBRICATION AND SCAVENGE OIL PUMP
IDG
IDG AIR/OIL HEAT EXCHANGER
IDG AIR/OIL HEAT EXCHANGER BYPASS VALVE
FUEL/OIL COOLER
ENGINE AIR/OIL HEAT EXCHANGER
ANGLE GEARBOX
MAIN GEARBOX SCAVENGE OIL INLET
NO. 1, 1.5, AND 2 BEARING SCAVENGE OIL INLET
ANGLE GEARBOX SCAVENGE OIL INLET
NO. 4 BEARING SCAVENGE OIL INLET
NO. 3 BEARING SCAVENGE OIL INLET
NO. 1, 1.5, AND 2 BEARING COMPARTMENT
NO. 1 BEARING
NO. 1 BEARING SEAL
NO. 1.5 BEARING
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