Helio H 295 N6464V accident near Fairbanks, Alaska

Probable cause

Excessive side loads imposed on the tailwheel A-frame during the takeoff roll, which resulted in a separation of the tailwheel and the subsequent loss of directional control.

NTSB analysis

The airline transport pilot was departing from a remote unimproved airstrip. He stated that, as he initiated the takeoff, everything seemed normal. About 300 ft into the takeoff roll, the airplane veered sharply left, exited the airstrip, and impacted brush and trees, which resulted in substantial damage to the fuselage and left horizontal stabilator. A postaccident examination of the airplane revealed that the tailwheel had separated from its attachment point and folded underneath the empennage.

Visual and magnified optical examinations revealed deformation and fracture patterns consistent with an overstress failure. Although fatigue cracks were observed in the fractured left arm of the tailwheel A-frame, they were relatively small and would not likely have caused a failure without abnormal loading. Additionally, the fractures in the left arm initiated not only at the fatigue cracks but also at locations away from the fatigue cracks, consistent with an overstress fracture. It is likely that the tailwheel A-frame fractured due to excessive side loads on the frame, which led to the tailwheel separating and the subsequent loss of control.

Text from the NTSB. Open the NTSB docket for ANC16LA067 for the full record.