Aviation Safety Advisory A17C0132-D1-A1

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01 June 2018

Aviation Safety Advisory A17C0132-D1-A1
Related occurrence: A17C0132

Letter addressed to Transport Canada

On 02 November 2017, a Perimeter Aviation LP Fairchild SA227-AC Metro III (serial number AC-756B, registration C-FLRY) was operating as flight 959 (PAG959) from Gods River, Manitoba, to Thompson, Manitoba, with 2 crew members on board. When the aircraft was approximately 40 nautical miles southeast of Thompson, the crew advised air traffic control that they had received a low oil pressure indication on the left engine and that they may be required to shut down the engine. The crew did not declare an emergency, but aircraft rescue and firefighting was put on standby. After touchdown on Runway 24 with both engines operating, the aircraft suddenly veered to the right and exited the runway. The aircraft came to rest north of the runway in the snow. The pilot and co-pilot exited the aircraft through the left side over-wing emergency exit and were taken to hospital with minor injuries. The aircraft sustained substantial damage. The occurrence took place during the hours of darkness, at 1920 Central Daylight Time. TSB investigation A17C0132 is ongoing and is currently in the report writing phase.

Inspection of the left engine (Garrett TPE331-11U-612G) revealed a near total loss of engine oil. A subsequent teardown of the engine revealed excessive oil soot and oil coking^{Footnote 1} of the rear turbine air-oil seal. The excessive oil soot and oil coking is indicative of an oil leak.

The emergency procedures specified in the SA227-AC Metro III Aircraft Flight Manual (AFM) state the following:

"L or R OIL PRESS (RED) - Corresponding engine oil pressure is less than 40 psi. Monitor engine instruments."

Adherence to the current emergency procedure listed in the AFM may lead to continued operation of the engine with low oil pressure. Continued operation of the engine with decreasing engine oil pressure to a critically low value will result in an adverse propeller response that could lead to a loss of control of the aircraft.

This occurrence demonstrates the importance of establishing specific procedures/criteria in the AFM for engine shutdown in the event of a low oil pressure indication. Therefore, Transport Canada is encouraged to work with the manufacturer to amend the oil low pressure emergency procedures currently contained in the AFM.

The TSB would appreciate being advised of Transport Canada's position on this issue, and what, if any, action is taken in this regard. Upon completion of investigation A17C0132, the Board will release its investigation report into this occurrence.

Sincerely,

Original signed by

Natacha Van Themsche
Director of Investigations – Air

Cc.

NTSB
FAA
Elbit Systems America
Honeywell Aerospace
Perimeter Aviation

Background information

Occurrence No.: A17O0264

This Safety Communication No.: A17C0132-D1-A1

Contact:

Eckhard Dittbrenner
Investigator-in-Charge, Central Office
Transportation Safety Board of Canada