Incident Overview
On 25 November 2021, Amapola Flyg AB flight APF322, a passenger aircraft scheduled from Helsinki-Vantaa to Joensuu, experienced an engine malfunction during takeoff. The crew initiated the takeoff roll on runway 22L at 15:06 UTC. Moments before reaching decision speed V1, the aircraft's Integrated Alerting Unit (IAU) emitted two chimes, the second shorter than the first, and a warning light on the Central Annunciator Panel (CAP) illuminated briefly. Neither pilot identified the source before the light extinguished.
Takeoff and Warning
After V1 was reached, the captain (pilot flying) rotated the aircraft at Vr. Simultaneously, a Master Warning (MW) activated with a warning light and three audio alerts. Following takeoff, the landing gear was retracted on command.
Post-Takeoff Actions
The malfunction led the crew to return to Helsinki-Vantaa. The flight data recorder and cockpit voice recorder were analyzed. The German BFU downloaded flight recorder data, and Canadian engine manufacturer Pratt & Whitney tested the Auto Feather Unit (AFU). The investigation involved accredited representatives from the Dutch Safety Board (DSB), Canadian Transportation Safety Board (TSB), Swedish Accident Investigation Authority (SHK), and a technical advisor from the European Union Aviation Safety Agency (EASA).
Investigation Findings
The investigation focused on the engine malfunction, specifically the auto feathering system and engine control units. Safety recommendations were issued regarding propeller auto-feather logic, engine control unit operation, crew training, and checklist supplements. No probable cause was stated in the report excerpt.