MD Helicopters 369D - Page 248

CSP-HMI-3 MD Helicopters, Inc.
MAINTENANCE MANUAL
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Copyright © 1999−2016 by MD Helicopters, Inc.
Table 201. Troubleshooting Electrical System (Cont.)
Symptom Corrective ActionProbable Trouble
Starter−generator fails to supply
charging current with engine
operating
Circuit breaker out Reset circuit breaker.
Reverse current relay defective or
*GCU
Replace reverse current relay or
*GCU.
Excessive discharge rate Check for cause of excessive
discharge rate.
Charging rate to high Adjust voltage regulator or *GCU.
Starter−generator defective (Check
for sheared armature drive shaft
through air inlet screen)
Replace sheared drive shaft (Refer
to manufacturer’s publication − Ref.
Sec. 01−00, Table 201)
Voltage regulator or *GCU
defective
Replace voltage regulator or *GCU.
Voltage regulator or *GCU
incorrectly adjusted
Adjust voltage regulator or *GCU.
Overvoltage relay defective or
*GCU
Replace overvoltage relay or *GCU.
GEN−OFF switch defective Replace switch.
Defective wiring Repair or replace defective wiring.
*Defective aft/fwd line contactor *Replace aft/fwd line contactor.
Ammeter indication off−scale below
zero; engine not operating and
GEN−OFF switch is on
Defective reverse current relay or
*GCU
Replace reverse current relay or
*GCU.
GEN−OUT indicator light on;
voltage lower than normal when
engine is operating
Weak generator field Replace starter−generator.
Defective voltage regulator or
*GCU
Replace voltage regulator or *GCU.
Defective starter−generator Replace or repair starter−generator.
Incorrectly adjusted voltage
regulator or *GCU
Adjust voltage regulator or *GCU.
Fluctuating current indication on
ammeter
Unstable voltage regulator or *GCU Replace voltage regulator or *GCU.
Brushes excessively worn Replace starter−generator brushes.
Defective starter−generator Replace or repair starter−generator.
Loose ammeter circuit wiring or
defective resistor R500 if installed
(R500 used with early model
instrument clusters − 369D S/N
003−723 only)
Check ammeter circuit connections
and resistor R500 if installed. Repair
or replace as necessary.