Pilot Debrief

PIPER PA-18-150 near Paxon, AK — 2012-04-28

Final reportANC12TA035
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Date
2012-04-28
Location
Paxon, AK, USA
Aircraft
PIPER PA-18-150
Registration
N7059
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Landing

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 narrative

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.

Analysis

Primary failure mode
Mechanical failure

NTSB coding

Evidence available

  • 3 docket documents
View NTSB final reportView NTSB docket

Docket documents3

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