What happened
On 26 November 2020, an ATR 42-300, registered as C-FAFS, was operating a scheduled flight from Rankin Inlet, Nunavut, to Naujaat, Nunavut. The flight, operated by Avions de Transport Régional, was being conducted under instrument flight rules with three crew members on board.
During the descent phase of the flight, the crew noticed that the propeller RPM on the left engine was indicating abnormally low values. Upon landing on Runway 34 at Naujaat Airport, the aircraft lost directional control. This resulted in a runway excursion where the plane veered off the east side of the runway, eventually coming to a stop roughly 108 feet from the runway edge. The captain sustained serious injuries, and the aircraft suffered substantial damage.
The investigation
The investigation focused on the mechanical behavior of the left engine's propeller and the subsequent loss of control during the landing roll. Investigators examined the sequence of events starting from the detection of low RPM indications during the approach and the aircraft's behavior immediately following touchdown.