Incident Overview
On June 26, 2012, an ATR-72 aircraft (type as per report) departed from Gdańsk Lech Wałęsa Airport (EPGD) en route to Poznań-Ławica Airport (EPPO). After reaching the intended altitude and speed, the crew selected the power lever to the CRUISE position. At that moment, unusual sounds and unstable operation of engine No. 1 were noticed. On both the Crew Alerting Panel (CAP) and the local panel, the OIL LOW PRESS warning appeared. The crew proceeded to shut down engine No. 1.
Shortly thereafter, the CAP displayed an ELECTRICAL SMOKE warning. A strong smell of burnt oil was detected in the cabin, and smoke entered the cabin. The crew performed the OIL LOW PRESS and ELECTRICAL SMOKE checklists as per procedures. Following the SINGLE ENGINE procedure, the crew declared an emergency and landed safely at Poznań. No injuries occurred among the 37 persons on board.
Investigation Findings
Post-flight inspection of engine No. 1 revealed a loss of oil from the tank. Further examination identified an improperly installed and secured oil filler cap. The investigation reviewed maintenance activities from 2012 that could have affected the oil system. It was determined that the day before the incident, an oil replenishment task was performed. During that task, the oil filler cap may have been incorrectly installed and secured. A defect in the cap or tank was ruled out as a contributing factor.
The engine could not be restarted; it was removed and replaced with another engine.
Probable Cause
The probable cause of the incident was the improper installation and securing of engine No. 1's oil filler cap during an oil replenishment task performed the day before the incident, which led to oil loss, engine damage, and the need to shut down the engine in flight.
Preventive Actions
The operator took the following preventive measures:
- A discussion was held with the maintenance manager to determine any circumstances that may have contributed to the improper installation of the oil filler cap.
- A Quality Information Letter was issued with guidelines for maintenance personnel.
No safety recommendations were issued by the investigation commission.