Service difficulty report · Control Unit · Dhav DHC8102

Difficulty date
July 5, 2014
Submitted
March 12, 2015
Operation
General aviation
Make and model
Dhav DHC8102
Aircraft time
59,789 hours
Engine
Pwa PW120A
Propeller
Hamstd 14SF7
Part
Control Unit
Part number
7898426009
Condition
Malfunctioned
Location
Engine
Stage of operation
CR
How discovered
O
Nature of condition
R, J
Precautionary procedure
E, A

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

What was found

(CAN) IN CRUISE, FLIGHT CREW OBSERVED TORQUE FLUCTUATION ON THE NR 2 ENGINE ASSOCIATED WITH NOTICEABLE YAW MOVEMENT. DECISION WAS TAKEN TO SHUTDOWN THE ENGINE, THE CHECKLIST WAS INITIATED BUT BY THE TIME IT WAS COMPLETED THE ENGINE HAD STOPPED ON ITS OWN. AN EMERGENCY WAS DECLARED, THE ACFT DIVERTED TO THE NEAREST SUITABLE AIRPORT AND LANDED WITHOUT FURTHER INCIDENT. AT THE TIME OF THE INCIDENT, THE ACFT WAS OPERATING UNDER MEL 73-2-1X DUE TO TORQUE FLUCTUATION ON NR 2 ENGINE WITH ENGINE ELECTRONIC CONTROL UNIT (EECU) SELECTED ON. DURING TROUBLESHOOTING, IT WAS NOTICED THAT THE MEL WAS INCORRECTLY APPLIED. THE MEL REQUIRES THAT ASSOCIATED EECU DC ESSENTIAL BUSSES CIRCUIT BREAKERS (CB) BE PULLED AND COLLARED. 1 OF THE CBS WAS FOUND CLOSE. ENGINE CONDITION WAS REPRODUCED DURING ENGINE GROUND RUNS BY OPENING/CLOSING THE CB, RT ESS BUS H3. THE EECU WAS REPLACED, TESTED AND THE ACFT RELEASED FOR SERVICE.