Service difficulty report · Relay · Bell 407

Difficulty date
June 22, 2011
Submitted
June 22, 2011
Operation
General aviation
Aircraft
N911VS
Make and model
Bell 407
Aircraft serial
53650
Aircraft time
3,831 hours, 6,029 cycles
Part
Relay
Part number
SM20ACD300A21
Condition
Unserviceable
Location
Dc Power
Stage of operation
CR
How discovered
O
Nature of condition
H
Precautionary procedure
O

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

WHILE ENROUTE, ATTEMPT WAS MADE TO START SEARCHLIGHT. UPON NOTICING SEARCHLIGHT DID NOT LIGHT OFF, CHECKED INSTRUMENTS AND FOUND VOLTMETER BELOW 25VDC. ATTEMPT WAS MADE TO RESET GEN WITH NO SUCCESS, NOTICED AMMETER AT ZERO, RETURNED TO AIRPORT WITHOUT INCIDENT. NEXT MORNING INSPECTED AND PERFORMED GROUND RUN TO TROUBLESHOOT SYSTEM, FOUND GEN OUTPUT AT 28VDC, NO AMPERAGE, AND NO GEN FAULT MASTER CAUTION LIGHT ILLIMINATED. THESE INDICATORS LED TO BELIEVE THE GEN RELAY AT FAULT. ACCESS WAS MADE TO DC POWER PANEL FS 155 AND NOTICED DISCOLORATION OF THE COVER. REMOVED COVER AND FOUND WIRE P20A12 BETWEEN 2K3 GEN RLY AND 15A CIRCUIT BREAKER 2CB6, "GEN FIELD" HAD MELTED INSULATION AT THE BUSS BAR, AND WIRE D10A22 BETWEEN 5A CIRCUIT BREAKER 2CB2 "AMMETER" AND 2R1 SHUNT TO HAVE A MELTED WIRE TERMINAL AT THE SHUNT. NEITHER CB HAD OPENED.

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