Service difficulty report · Relay · Swrngn SA226TC

Difficulty date
December 1, 2009
Submitted
January 19, 2010
Operation
General aviation
Make and model
Swrngn SA226TC
Aircraft time
23,571 hours
Engine
Garrtt TPE33110UA
Part
Relay
Part number
6041H205A
Condition
Malfunctioned
Location
Generator
Stage of operation
CR
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

(CAN) CREW ARRIVED AFTER ONE HOUR FLIGHT REPORTING ABNORMAL LT GENERATOR VOLT METER INDICATION. THE GEN FAIL LIGHT FUNCTIONED NORMALLY WITH THE GENERATOR OFF OR ON, HOWEVER, THE GENERATOR WOULD NOT SUPPLY THE BUS, THIS WAS CONFIRMED ON A GROUND RUN CHECK. AFTER SOME INVESTIGATION MAINTENANCE FOUND A BURNT WIRE FROM THE GENERATOR RELAY’S X2 POST (COIL) TO GROUND. THE INSULATION HAD BURNT OFF IT AND ALSO DAMAGED OTHER WIRES IN THE BUNDLE. THE WIRING WAS MODIFIED IN THIS AREA BY AD 97-11-13 AND VARIOUS SERVICE BULLETINS INCORPORATED BY THAT AD. IT WAS DETERMINED THAT THE MOST LIKELY CAUSE WAS THE FAILURE OF THE GENERATOR RELAY, CAUSING THE MAIN CONTACTOR INSIDE TO TOUCH THE GEN FAIL INDICATOR CONNECTIONS ON THE TOP OF THE RELAY. THIS PROVIDED A DIRECT PATH TO GROUND THROUGH THE X2 POST OF THE RELAY AND CAUSED THE BURNT WIRE. THIS RELAY CAN BE REPLACED BY SB 226-24-033, HOWEVER, THAT HAS NOT BEEN ACCOMPLISHED ON THIS AIRFRAME. THE OPERATOR IS ISSUING A NOTICE TO INSPECT ALL AFFECTED AIRFRAMES AT NEXT ACCESS, AND A CAMPAIGN TO REMOVE THE X2 WIRE FROM THE BUNDLE AND ROUTE IT SEPARATELY SO IN THE EVENT OF A FAILURE, THIS WIRE WILL NOT DAMAGE ANY OTHER WIRING. (TC NR 20091202011)