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Accident description
Last updated: 15 December 2017
Status:Final
Date:Wednesday 4 February 2009
Time:09:15
Type:Silhouette image of generic DHC6 model; specific model in this crash may look slightly different
de Havilland Canada DHC-6 Twin Otter 100
Operator:Transwest Air
Registration: C-FCCE
C/n / msn: 8
First flight: 1966
Engines: 2 Pratt & Whitney Canada PT6A-20
Crew:Fatalities: 0 / Occupants: 2
Passengers:Fatalities: 0 / Occupants: 5
Total:Fatalities: 0 / Occupants: 7
Airplane damage: Substantial
Location:La Ronge Airport, SK (YVC) (   Canada)
Phase: Takeoff (TOF)
Nature:Domestic Non Scheduled Passenger
Departure airport:La Ronge Airport, SK (YVC/CYVC), Canada
Destination airport:Deschambeault Lake, SK, Canada
Narrative:
The Transwest Air spring ski-equipped de Havilland DHC-6-100 (registration C-FCCE) was taking off from a ski strip east of and parallel to runway 36 at La Ronge Airport, SK (YVC). After the nose ski cleared the snow, the left wing rose and the aircraft veered to the right and the captain, who was the pilot flying, continued the takeoff. The right ski, however, was still in contact with the snow. The aircraft became airborne briefly as it cleared a deep gully to the right of the runway. The aircraft remained in a steep right bank and the right wing contacted the snow-covered ground. The aircraft flew through a chain link fence and crashed into trees surrounding the airport. The five passengers and two crewmembers evacuated the aircraft with minor injuries. There was a small fire near the right engine exhaust that was immediately extinguished by the crew.

Probable Cause:

FINDINGS AS TO CAUSES AND CONTRIBUTING FACTORS:
1. Contamination on the wings of the aircraft was not fully removed before take-off. It is likely that asymmetric contamination of the wings created a lift differential and a loss of lateral control.
2. Although the operator was not authorized for short take-off and landing (STOL) take-off on this aircraft, the crew conducted a STOL take-off, which reduced the aircraft's safety margin relative to its stalling speed and minimum control speed.
3. As a result of the loss of lateral control, the slow STOL take-off speed, and the manipulation of the flaps, the aircraft did not remain airborne and veered right, colliding with obstacles beside the ski strip.

FINDINGS AS TO RISK
1. The out of phase task requirements regarding the engine vibration isolator assembly, as listed in the operator's maintenance schedule approval, results in a less than thorough inspection requirement, increasing the likelihood of fatigue cracks remaining undetected.
2. The right engine inboard and top engine mounts had pre-existing fatigue cracks, increasing the risk of catastrophic failure.

OTHER FINDINGS
1. The cockpit voice recorder (CVR) contained audio of a previous flight and was not in operation during the occurrence flight. Minimum equipment list (MEL) procedures for logbook entries and placarding were not followed.
2. The Transwest Air Limited safety management system (SMS) did not identify deviations from standard operating procedures.

Accident investigation:
cover
Investigating agency: TSB Canada
Status: Investigation completed
Duration: 1 year
Accident number: A09C0017
Download report: Final report

Classification:
Icing
Loss of control

Sources:
» CADORS Number: 2009C0305


Photos

photo of de Havilland Canada DHC-6 Twin Otter 100 C-FCCE
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Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from La Ronge Airport, SK to Deschambeault Lake, SK as the crow flies is 118 km (74 miles).
Accident location: Exact; deduced from official accident report.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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