79-32-02
 INDICATORS  ú ú C02 Page 403 ú Mar 12/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
LOW OIL PRESSURE WARNING SYSTEM - DESCRIPTION AND OPERATION
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 1.  General
_______
 A.  The low oil pressure warning system provides an indication in the flight compartment of low engine oil pressure. The system consists of a low oil pressure warning switch and a low oil pressure warning light.
 2.  Low Oil Pressure Switch (Fig. 1)
_______________________
 A.  The low oil pressure warning switch is a snap action, pressure-sensitive switch. It is connected in parallel with the oil pressure transmitter to oil supply pressure and vent pressure lines.
 B.  The low oil pressure warning switch is mounted on a bracket on the fan case just forward of flange K at the 10 o'clock position.
 3.  Low Oil Pressure Warning Light (Fig. 1)
______________________________
 A.  There are two amber low oil pressure warning lights located on the pilots center instrument panel, P2, one for each engine. The light illuminates when the engine oil pressure drops below a specified limit.
 4.  Operation (Fig. 1 and 2)
_________
 A.  28 volts dc power is supplied to the low oil pressure warning system from the P6-3 circuit breaker panel.
 B.  The low oil pressure warning switch remains open above 15.25 psig and closes if the oil pressure drops below 12.25 psig. When it closes, the warning circuit is completed and the low oil pressure warning light illuminates.
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 79-33-00
 ALL  ú ú C03 Page 1 ú Mar 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
SEE A
ELECTRICALCONNECTOR
OIL PRESSURE TRANSMITTER
LOW OIL PRESSURE WARNING SWITCH
LOCKWIRE
ELECTRICAL 
CONNECTOR 
OIL SUPPLY  VENT PRESSURE TUBE 
PRESSURE  FROM THE TGB 

FWD
A

Low Oil Pressure Warning System - Component Location
Figure 1 (Sheet 1)

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 79-33-00
 ALL  ú ú C03 Page 2 ú Mar 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / /
CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////
SEE A
LOW OIL PRESSURE LOW OIL PRESSURE WARNING LIGHT WARNING LIGHT
START VALVE START VALVE 
OPEN  A  OPEN  A 
LOW OIL  OIL FILTER  LOW OIL  OIL FILTER 
PRESSURE  A  BYPASS  A  PRESSURE  A  BYPASS  A 

PILOTS CENTER INSTRUMENT PANEL
A

Low Oil Pressure Warning System Component Location
Figure 1 (Sheet 2)

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 79-33-00
 ALL  ú ú C01 Page 3 ú Mar 15/94
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
////////////////////////A / /
CFM56 ENGINES
737-300/400/500/ /MAINTENANCE MANUAL ////////////////////////

P6-3 LOAD P2-2 CENTER INSTRUMENT PANEL ENGINE 1 CONTROL CENTER
Low Oil Pressure Warning System Schematic
Figure 2 (Sheet 1)

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