Piper PA-18-150 N7059 accident near Paxon, Alaska

Probable cause

A separation of the right main landing gear suspension strut assembly due to overstress, which resulted in the collapse of the main landing gear while landing.

NTSB analysis

The pilot said he was landing a ski-equipped airplane on a remote, frozen and snow-covered lake. He said that as the skis contacted the flat and smooth snow-covered ice, the airplane pitched forward violently, then to the right, and then back to the left. A postaccident examination revealed that the right main landing gear had collapsed and subsequently folded under the airplane. An examination of the right main landing gear revealed a fractured suspension strut that had fractured laterally across a bored and threaded area of the suspension tube. The fractured tube was examined under magnification and there was no evidence of external corrosion. The tube had a long radius bend adjacent to the internal threads. The fracture had a clean, evenly colored fracture surface, and no evidence of repeated fracturing (beach marking). The fracture appearance is consistent with an overstress fracture. The pilot noted that, other than the fractured main landing suspension strut, there were no preaccident mechanical anomalies with the airplane.

Text from the NTSB. Open the NTSB docket for ANC12TA035 for the full record.