Cessna 150C N1901Z accident near Juneau, Alaska

Probable cause

The collapse of the left main landing gear during the landing roll, as a result of fatigue cracking. Contributing to the accident was the improper maintenance of the landing gear.

NTSB analysis

The flight instructor was demonstrating a short field, three-point landing. The touchdown was normal, but during the landing roll a gust of wind pushed the airplane, and it began to turn to the right. The instructor applied left brake in an attempt to correct for the right turn, and the airplane’s left main landing gear broke. As the broken gear leg dug into the runway, the airplane pivoted 180 degrees to the left, and the left wing struck the runway. The airplane sustained substantial damage to the left wing and fuselage. The flight instructor stated that during the last annual inspection, about 4 months before the accident, he observed corrosion on the main landing gear legs and ground it off using a hand-held grinder. The service manual specified to carefully remove any rust by light sanding; the sanding must blend the damage into the adjacent area in an approximate 20:1 ratio. Examination of the landing gear revealed evidence of the improper maintenance and corrosion damage, which weakened the gear and led to fatigue cracking and an overstress fracture.

Text from the NTSB. Open the NTSB docket for ANC13LA016 for the full record.