CSP-HMI-3 MD Helicopters, Inc.
MAINTENANCE MANUAL
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purpose except as specifically authorized in writing by MD Helicopters, Inc.
Copyright © 1999−2016 by MD Helicopters, Inc.
Table 103. Instrument Troubleshooting
Symptom Probable Trouble Corrective Action
Three−Pack Indicating System
Engine oil temperature pointer off
either end of scale or does not
respond
Open or short circuit in indicator Replace instrument cluster.
Open or short circuit in wiring
harness
Replace wiring.
Defective resistor R1
(early instrument cluster only)
Replace defective resistor.
Defective sender Replace sender.
No reading or erratic ammeter
reading
Malfunctioning voltage regulator Replace voltage regulator.
Defective resistor R500
(early instrument cluster only)
Replace defective resistor.
Loose connector, open or short
circuit in wiring
Tighten connector or replace wiring.
Dirty or worn mechanism in ammeter Replace instrument cluster.
Open or short circuit in ammeter Replace instrument cluster.
NOTE
: The tank sending unit is potted with sealant (CM425) to prevent shorting due to moisture accumulation.
Fuel quantity indicator inaccurate,
erratic or inoperative
Wires loose, shorted or open
Check tank unit electrical
connections; repair as necessary.
Check electrical wires between tank
unit and instrument cluster. Repair as
necessary.
Fuel indicator or tank unit defective Perform operational check (Ref. Sec.
28−00−00). Replace instrument
cluster or tank unit.
Defective resistor R1
(early instrument cluster only)
Replace defective resistor.
Ammeter
No reading or erratic reading
Malfunctioning voltage regulator VR1 Replace voltage regulator.
Loose connector, or open or short
circuit in wiring
Tighten connector or replace wiring.
Dirty or worn mechanism in ammeter Replace ammeter.
Open or short circuit in ammeter Replace ammeter.
High reading
(369D S/N 003 − 1149)
Excessively high resistance reading
between battery relay and reverse
current relay; 3−#10 wires, not to
exceed resistance of 3.64 milliohms
Inspect terminal lugs joining wires,
clean or repair as necessary.
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