What happened
During a visual flight from Chevery, Quebec, to Tête-à-la-Baleine, Quebec, a Régionair Inc. Twin Otter experienced a landing accident on a frozen, hard-packed sandy runway. While the co-pilot was operating the aircraft, the plane touched down at approximately 60 knots with flaps set at 37.5 degrees. Upon initial contact with the runway, the aircraft bounced roughly 160 feet.
Following a second touchdown, the nosewheel assembly failed. This mechanical failure caused the aircraft to veer toward the left side of the runway, eventually coming to a stop off the paved surface. There were no injuries reported among the crew or passengers.
The investigation
Investigators examined the runway conditions and the aircraft's nosewheel assembly. The runway, oriented 360 degrees magnetic, measured 1,320 feet in length and 65 feet in width. While the surface was even and free of holes, it was frozen. Meteorological data indicated that winds were blowing from approximately 300 degrees magnetic, creating a crosswind at a 60-degree angle to the runway with strong gusts.
Technical analysis of the nosewheel focused on the piston and its attachment to the fork. The TSB Engineering Branch Laboratory confirmed that the piston was manufactured according to all required specifications and found no evidence of pre-existing fatigue. The investigation determined that the piston fractured in the threaded section where it connects to the fork.
Findings
- The aircraft landed heavily with a significant crab angle due to the wind conditions.
- The initial touchdown on the frozen surface caused the aircraft to bounce a considerable distance.
- The nosewheel piston failed due to an overload caused by lateral forces applied from the right side.
- Strong, gusty crosswinds contributed to the lateral forces that forced the nosewheel to bend to the left during the landing sequence.