Propeller malfunction led to 2020 runway excursion in Naujaat, Nunavut
Winnipeg, Manitoba, 1 November 2022 — In its investigation report (A20C0107) released today, the Transportation Safety Board of Canada (TSB) identified multiple contributing factors leading to a 2020 runway excursion in Naujaat, Nunavut.
On 26 November 2020, a Calm Air International LP Avions de Transport Régional ATR 42-300 aircraft was conducting a flight from Rankin Inlet, Nunavut, to Naujaat, Nunavut, with three crew members on board. While on descent to Naujaat Airport, the crew observed abnormally low propeller rpm indications on the left engine. Shortly after touchdown, directional control was lost and the aircraft experienced a runway side excursion on the east side of the runway. The aircraft came to rest approximately 108 feet from the runway edge and sustained substantial damage. The captain received serious injuries.
The investigation determined that a contaminant inside the left propeller’s high-pressure pump caused its pressure relief valve to fail. As a result, the propeller entered a pitch-lock condition, which locks the blade pitch and prevents reverse thrust from activating. The propeller remained in that condition until the aircraft landed. The investigation also determined that because there is no indication in the cockpit of a pitch-lock condition in flight, the flight crew were not aware that the propeller had entered a pitch-lock condition. Immediately on touchdown, reverse thrust was selected by the pilot flying, resulting in the aircraft entering an asymmetric thrust state. Due to the asymmetric thrust, directional control of the aircraft could not be maintained, and the aircraft exited the landing surface of the runway.
Following the occurrence, the operator issued a Flight Operations Bulletin, which describes the condition known as pitch lock, possible causes for this condition, how to identify it, and the actions to be taken if this condition is suspected.
For more information, see the investigation page.
The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada