Service difficulty report · Relay · Cessna 650

Difficulty date
October 7, 2003
Submitted
October 28, 2003
Operation
Air carrier
Aircraft
N72ST
Make and model
Cessna 650
Aircraft serial
6500072
Engine
Garrtt TFE731*
Part
Relay
Part number
99104771
Condition
Burned
Location
Apu Starter
Part time
6,209 hours
Stage of operation
NR
How discovered
9
Nature of condition
O
Precautionary procedure
O

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

What was found

DURING MAINTENANCE GROUND RUN, ATTEMPTED TO START APU. APU DID NOT START. ON NEXT ATTEMPT TO START, APU DID NOT START AND START RELAY WOULD NOT DISENGAGE. BEFORE POWER COULD BE SHUT OFF BY DISCONNECTING SHIPS BATTERIES, NOTICED SMOKE COMING FROM APU J-BOX. UPON FURTHER INSPECTION, FOUND APU POWER RELAY (K114) WELDED OR MELTED IN CLOSED POSITION. THIS CAUSED AN OVERHEAT CONDITION OF RELAY CAUSING SEVERAL OTHER COMPONENTS TO BE DAMAGED WITHIN J-BOX AND ASSOCIATED WIRING. ALSO FOUND WIRES WITH DAMAGE IN THE IMMEDIATE AREA AND/OR CHANGE INTERVAL INSTITUTED TO PREVENT RELAYS FROM DETERIORATING TO THE POINT OF CAUSING THIS CONDITION.(K)

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