The Avions de Transport Régional ATR 42-300 was descending to land at Naujaat, Nunavut, Canada, when the flight crew observed indications of abnormally low propeller rpm on the left engine. After touching down, they lost directional control, and the airplane veered off the runway.
The Transportation Safety Board of Canada (TSB) cited a condition known as pitch-lock, in which the blade’s pitch cannot be altered and reverse thrust cannot be activated. TSB traced the problem to a contaminant inside the left propeller high-pressure pump, which caused the pressure relief valve to fail.
The captain — one of three crewmembers in the airplane, which carried no passengers — was seriously injured and the first officer and flight attendant received minor injuries in the Nov. 26, 2020, accident, which substantially damaged the ATR 42.
The pilots were unaware of the problem because there was no cockpit indicator to warn that the pitch-lock was present, the TSB repo…
