What happened
During the landing rollout, the pilot applied the brakes, at which point the left wheel separated from the main landing gear. This mechanical failure caused the aircraft to veer toward the left side of the runway.
The investigation
The aircraft was equipped with a snow-ski adapter kit that had been installed on November 20, 1972. Upon touchdown, the four-wheel assembly retention bolts failed. Specifically, the upper two bolts sheared off first, and subsequently, the nuts were stripped from the lower two bolts. This sequence of failures resulted in the left landing gear wheel assembly separating from the landing gear strut.
Findings
Investigation into maintenance procedures revealed that there is currently no inspection criteria established for inspecting the wheel assembly retention bolts.