What happened
On March 12, 2017, a Piper PA44 180T, registration SP-MIS, was conducting an IR/ME training flight when the crew experienced vibrations in the left engine. This was accompanied by visible smoke appearing along the trailing edge of the wing. In response to the malfunction, the crew proactively shut down the left engine.
After notifying air traffic control of the technical issues—without declaring a formal emergency—the crew requested priority landing at EPMO. Approximately 7NM from the airport, the crew confirmed they would be landing with one engine inoperative. The flight lasted a total of 54 minutes, and the aircraft successfully landed on runway 08, taxiing under its own power to the parking stand.
The investigation
An investigation conducted by the operator's commission examined the aircraft following the incident. A post-flight inspection revealed significant internal damage, specifically to the engine turbine and the exhaust valve. Fragments from the damaged valve had subsequently destroyed the piston, necessitating the replacement of these components.
Findings
While the investigation could not definitively establish a single cause, investigators identified that the incident may have been caused by operating the aircraft on an overly lean fuel mixture during several flights preceding the March 12 occurrence. The investigation concluded that the crew's response to the engine failure was correct and that their actions did not directly contribute to the occurrence.