Multiple Factors Contributed to Serious Incident on Amapola Flight

The Safety In­ves­ti­ga­tion Au­thor­ity of Fin­land (SIAF) has com­pleted an in­ves­ti­ga­tion into the No­vem­ber 25, 2021, in­ci­dent in which a Fokker 50 op­er­ated by Amap­ola Flyg sus­tained an en­gine mal­func­tion on take­off at Helsinki-Van­taa air­port. The air­craft was de­part­ing on a sched­uled do­mes­tic ser­vice to Joen­suu.

A malfunction occurred in the feathering system of the left propeller during liftoff. The propeller feathered but the engine continued operation at high power.

“Aircraft can be flown safely on one engine”, explains Investigator-in-Charge Janne Kotiranta.

“In this particular event, a single anomaly would not have led to a serious incident, but multiple failures occurred, exacerbating the situation. The pilots noted the engine failure but did not realize immediately that the propeller had feathered. The engine continued running but did not produce thrust. The first officer eventually executed the prescribed procedure and shut down the engine. Also, the landing gear remained down throughout the entire flight, which in turn increased drag and degraded climb performance. The aircraft momentarily entered uncontrolled airspace, and nearly infringed safety margins around a tall transmission tower. To sum it all up, both technical and procedural discrepancies played a role in the event”, Kotiranta elaborates.

“The aircraft eventually landed back at the departure airport under air traffic control assistance. However, had this or any similar serious incident occurred in hot-and-high conditions, climb rate would have degraded further, and an accident could have resulted”, Kotiranta states.

Since the incident, Amapola Flyg has updated landing gear related instructions in the airplane flight manual.

Current pilot training does not include actions during uncommanded propeller feathering. The SIAF therefore recommends that these procedures be added in pilot training syllabi.

The SIAF also gave two safety recommendations to the aircraft manufacturer. Both are related to propeller feathering and feathering control.