TM 1-1520-238-T-4
Change 5
6–77
6–15.3. HOD NGB 1 READING – DISPLAYS 54 LB OIL PRESSURE OR LESS
6–15.3
Tools:
Nomenclature
Part Number
Tool Kit, Aircraft
SC518099CLA01
Mechanic’s
Tool Kit, Electrical
SC518099CLA06
Repairer’s
Adapter, Straight Pipe
A1100-4-4
to Tube, Female
Pipe End, 37 Flared
Gage Pressure, Dial
GGG76
Indicating
(0-200 PSI)
Tester, MP-1
6685-00-693-5009
Multimeter, Digital
AN/PSM-45
Personnel Required:
67R
Attack Helicopter Repairer
68X
Armament/Electrical Systems Repairer
152FG
Maintenance Test Pilot
References:
TM 1-1520-238-23
TM 1-1520-238-CL
TM 55-1500-323-24
TM 9-1230-476-20-2
Equipment Conditions:
Ref
Condition
TM 1-1520-238-23
Access provisions –
L200 access panel and
LN6 fairing open.
WARNING
Turn off power before detaching or
attaching wires and connectors. High
current 28 VDC or 115 VAC is present.
Failure to do so could result in death or
serious injury.
NOTE
A reading of 50 LB on the HOD is
generally a wiring problem.
Troubleshoot in accordance with Task
6–15.1 before proceeding.
1. Check pilot caution/warning panel OIL PSI
NOSE GRBX 1 indicator.
Is indicator lighted?
YES
Go to step 3.
NO
Go to step 2.
2. Remove NGB 1 oil pressure transducer (MT11)
(TM 1-1520-238-23). Connect MT11 to Tester,
MP–1. Observe HOD while applying pressure to
transducer with tester.
Does HOD reflect applied pressure within +/–
5 PSI from 0 to 100 PSI?
YES
Go to step 3.
NO
Replace NGB 1 oil
pressure transducer
(TM 1-1520-238-23).
Go to paragraph 6–13.
3. Install pressure gage GGG76 in NGB 1. Start
engine 1 and place PWR lever to FLY
(TM 1-1520-238-CL). Operate until readings
stabilize.
Is NGB 1 oil pressure 35 – 54 LB?
YES
Replace NGB 1 lube pump.
Remove gage GGG76 and
reinstall oil pressure transducer
(TM 1-1520-238-CL).
Go to paragraph 6–13.
NO
Replace NGB 1
(TM 1-1520-238-23).
Go to paragraph 6–13.
NOTE
If NGB 1 operating pressure was 28 PSI
or less and OIL PSI NOSE GRBX 1
indicator was not illuminated,
troubleshoot NGB 1 oil pressure switch.
END OF TASK
