What happened
During a repositioning flight from a marine dock to the Goose Bay Airport, a de Havilland DHC-6-300 Twin Otter, registration C-FIZD, struck a wooden safety curb during its takeoff roll. The aircraft was being moved following a conversion from float to wheel landing gear. As the pilots executed a maximum performance STOL takeoff, the nose gear encountered a depression in the dock surface, which momentarily reduced the wing's angle of attack and delayed rotation. This caused the right main landing gear to strike a 14-inch-high wooden curb at the dock's perimeter.
Following the impact, the crew performed an in-flight visual inspection and, believing the damage to be minimal, continued to the Goose Bay Airport. However, upon landing, the right main gear collapsed and separated from the aircraft. The aircraft veered off the runway and came to rest on a taxiway. There were no injuries to the two pilots on board.
The investigation
The investigation examined the takeoff performance, the physical conditions of the dock, and the aircraft's mechanical state. Investigators found that the actual takeoff distance available was 335 feet, which was shorter than the captain's estimate of 400 feet. The investigation also looked into the functionality of the aircraft's safety equipment, noting that the cockpit voice recorder was not recording due to a faulty inertial switch. Additionally, the emergency locator transmitter (ELT) was found detached from its mounting bracket due to the impact forces.
Findings
- The primary cause of the accident was that the available takeoff distance was shorter than estimated, which, combined with the performance loss caused by the dock depression, led to the landing gear striking the wooden curb.
- The right main landing gear collapsed during landing because of the damage sustained during the initial impact with the curb.
- A failure to follow company procedures—specifically the requirement to consult with the Director of Flight Operations regarding new takeoff sites—meant that risks associated with the dock takeoff might have been mitigated.
- The cockpit voice recorder was non-functional due to a faulty inertia switch, which could have resulted in the loss of critical data in a more severe event.
- The ELT mounting bracket used was an older version that was prone to detachment under impact.