Accident
During the takeoff roll at Glendive-Dawson County Airport, the pilot encountered engine trouble and decided to abandon the takeoff procedure. An emergency braking manoeuvre was attempted. The runway was covered with two inches of snow. The aircraft was unable to stop within the remaining distance, overran the runway, and came to rest down a bank. Six occupants were injured and a passenger was killed.
Investigation
Investigators determined that the engine failure was caused by a malfunction of the ignition system that was improperly secured. Additionally, issues were found with the engine structure and valve assemblies, including improper alignment or adjustment. The maintenance and inspection of the aircraft were found to be inadequate. The pilot was aware that the left magneto was inoperative and attempted operation with known deficiencies in equipment. During the takeoff, the number 4 cylinder exhaust valve failed.
Probable Cause
The probable cause of the accident was the combination of the following factors: - Engine failure caused by the malfunction of the ignition system which was improperly secured, - Engine structure, valve assemblies, - Improper alignment/adjustment, - Inadequate maintenance and inspection, - Runway covered by two inches of snow, - The pilot knew that the left magneto was inoperative and attempted operation with known deficiencies in equipment, - Number 4 cylinder exhaust valve failed during takeoff.