What happened
On the night of October 26, 2007, a privately operated Piper Malibu PA46-310P, registration C-GTCS, was performing an instrument flight rules (IFR) flight from Salem, Oregon, to Springbank, Alberta. While descending through 17,0/00 feet near Calgary, the pilot reported an engine failure to air traffic control.
Following the failure, the pilot attempted to reach the Fairmont Hot Springs airport in British Columbia. An overflying aircraft observed the plane attempting to navigate around a ridge but noted that the aircraft was unable to clear the terrain. Shortly thereafter, an emergency locator transmitter signal was detected. The aircraft crashed in wooded terrain near Invermere, British Columbia, at approximately 1912 mountain daylight time. The pilot and two passengers sustained three fatalities.
The investigation
The investigation focused on the mechanical state of the engine and the maintenance history of the aircraft. While the aircraft was otherwise well-maintained and within weight limits, investigators discovered that an unapproved, handmade flat washer had been used during a recent repair to the alternator drive coupling.
Additionally, the investigation looked into the engine's recent performance, noting that a knocking sound had been heard during flights earlier that summer, though this issue had not been documented in the aircraft's logbooks or reported to maintenance staff. The investigation also noted that the aircraft's IFR charts and approach plates had been expired for several months.