What happened
On January 3, 2017, a Saab-340A operated by SprintAir S.A. was performing an initial descent toward Kyiv-Zhulyany Airport (UKKK) in Ukraine. During this phase of flight, the flight crew discovered that the power lever for the number 2 (right) engine had become stuck in the cruise power position and could not be moved to any other setting.
Due to the inability to reduce power on the right engine, the crew decided to abort the approach to Kyiv and return to their home base at Warsaw Chopin Airport (EPWA). To manage the flight safely, the crew elected to shut down the number 2 engine while at an altitude of 10,000 feet. The aircraft subsequently performed a single-engine landing on runway 33 at EPWA, which was completed without further incident.
Prior to landing, the crew consulted with the operator's technical department to determine the appropriate procedure for shutting down the engine, as the specific scenario of an in-flight engine shutdown necessitated by an uncommanded power setting was not covered in the Quick Reference Handbook (QRH).
The investigation
The investigation focused on the mechanical failure of the engine control mechanism and the lack of established procedures for such an emergency. The investigation established that the physical cause of the lever jam was related to environmental factors affecting the control cables.
Findings
- The probable cause of the incident was the freezing of the right engine power lever control cables.
Safety action
Following the incident, the operator implemented several preventive measures:
- Flight personnel were briefed on the circumstances of the event.
- The operator initiated a program to clean and dry the Condition Lever and Power Lever control cables across the entire fleet during scheduled hangar maintenance.
- The maintenance interval for drying these cables was reduced from 8 years to 2 years, to be performed alongside control cable tension checks.
- The operator contacted the aircraft manufacturer to recommend an update to the Abnormal Checklist in the QRH to include procedures for handling engine power lever jams.