What happened
A private pilot was performing a landing on an off-airport grass surface area in a tundra tire-equipped airplane. During the landing roll, as the pilot applied the brakes, the left main landing gear collapsed. This caused the aircraft to pivot to the left, leading the left wing to strike the ground.
The investigation
An inspection of the landing gear revealed that the outboard end of the left main landing gear strut extension was broken through the outer radius of the attaching lug, which is the location where it normally bolts to the axle. The landing gear safety cable was also found to be broken.
The aircraft was equipped with hydrasorb landing gear shock units, which utilize automotive-type oleo struts combined with light shock cords. Upon examination of the outboard end of the hydrasorb extension tube, investigators found a flat fracture surface that was perpendicular to the long axis of the tube. This component showed extensive evidence of corrosion. Records indicated the landing gear had been installed since 1977, and the most recent annual inspection of the aircraft occurred approximately one year prior to the accident.