Accident Summary
On a multi-day cross-country training flight, an aircraft operated by the 8 Wing Multi Engine Utility Flight (MEUF) and owned by Air Tindi was involved in an accident during the first segment of its mission. The aircraft, coded as CT145D by the Royal Canadian Air Force, departed 8 Wing Trenton on an Instrument Flight Rule flight plan destined for Thunder Bay Airport, Ontario. Three military aircrew members were onboard.
Sequence of Events
After a routine climb and cruise, the aircraft was cleared for the RNAV Z 25 instrument approach into Thunder Bay. The crew configured the aircraft for the approach and utilized automation. Approximately two miles from the runway, with the airport in sight, the pilot elected to continue manually and disconnected the autopilot. As the aircraft crossed the runway threshold at approximately 50 feet above ground, the pilot flying moved both power levers to idle with the intent to land. Immediately, a left yaw developed followed by a rapid drop of the left wing. The pilot monitoring took control and initiated an overshoot, but the left wing tip contacted the runway surface and the aircraft continued uncontrollably into the snow-covered infield. After coming to rest, the three crew members egressed the aircraft.
Damage and Injuries
The aircraft sustained very serious damage. The pilot flying suffered a minor injury, while the other crew members were not injured.
Investigation Findings
Post-accident analysis of recovered flight data and componentry determined that the aircraft was documented serviceable prior to the flight and no issues were evident before the power levers were brought to idle. The investigation found that a part within the propeller speed governing system failed to function nominally—specifically, the beta valve or the beta solenoid. This led to the left-hand propeller windmilling, which was the most likely cause of the accident. Because the beta valve was damaged and internal parts lost during the accident sequence, a definitive determination of its serviceability could not be conducted.