2 fatalities

1981-02-27: De Havilland DHC-6 Twin Otter (C-FCSV) — Transport Canada — Valens, Canada

Valens, CanadaFlight

On February 27, 1981, a De Havilland DHC-6 Twin Otter (registration C-FCSV) operated by Transport Canada was involved in an aviation accident near Valens, Canada in flight. 2 people were killed. Investigators recorded the probable cause as: After the right fuel lever was selected to the OFF position to simulate an engine failure, the fuel lever for the left engine was inexplicably moved to the OFF position. This summary draws on records from the Bureau of Aircraft Accidents Archives (B3A); 5 related events involving the same aircraft type or operator are linked below.

Sourcesthe Bureau of Aircraft Accidents Archives (B3A)Primary reportUpdated 1781222914Data APIEditorial standards

A twin-engine aircraft on a VFR training flight crashed near Valens, Ontario after an engine failure simulation. Two occupants were killed and one seriously injured. Investigators found that the left fuel lever was inexplicably moved to OFF.

Accident Summary

A twin-engine airplane operating a local VFR training flight crashed south of Valens, Ontario, resulting in two fatalities and one serious injury. The aircraft departed Toronto International Airport's Runway 23R at 1351 local time with three Civil Aviation Inspectors aboard: a captain in the left seat, a check pilot in the right seat, and an observer pilot in the right forward cabin seat. The purpose of the flight was to evaluate the captain's proficiency and renew his instrument rating.

Sequence of Events

After being cleared to climb to 3,000 feet, the crew was instructed to clear the frequency at 1358, approximately 22 nautical miles from Toronto. The flight test then began, including exercises such as a simulated approach and overshoot with a simulated engine failure during the overshoot. During a second such exercise, the right engine was shut down and an overshoot was initiated. A ground witness later observed that the right propeller was stopped and black smoke was emanating from the left engine. As the aircraft commenced a shallow descending right turn, the smoke diminished. The descent continued, and the aircraft struck trees before impacting the ground with its right main gear and nose. The accident site was located at 43° 22' N 80° 08' W, south of Valens.

Investigation Findings

The investigation identified the following findings: After the right fuel lever was selected to the OFF position to simulate an engine failure, the fuel lever for the left engine was inexplicably moved to the OFF position. The altitude above ground level selected for engine shutdown using the fuel shut-off lever provided insufficient margin for safety. The crew was current on type according to Department of Transport operating requirements. The report noted that improved Transport Canada requirements and operational control would help to prevent recurrence of this type of accident.

Probable cause

After the right fuel lever was selected to the OFF position to simulate an engine failure, the fuel lever for the left engine was inexplicably moved to the OFF position. Under these circumstances the altitude above ground level selected for engine shutdown using the fuel shut-off lever provided insufficient margin for safety. The crew was current on type according to DOT operating requirements. Improved Transport Canada requirements and operational control would help to prevent recurrence of this type of accident.