Accident Details
During the landing roll, the airplane's left main landing gear began to wobble and ultimately separated from the fuselage. The failed landing gear section was held in place by a through bolt near the center of the fuselage and a u-bolt at the point where the landing gear exited the fuselage.
Bolts Examination
Examination of the failed bolts revealed corrosion pitting and that the bolts had failed by overload. The corrosion pitting likely weakened the bolts, making them susceptible to overload under normal landing loads.
Maintenance History
According to the airplane owner, the bolts had been in place for 20 years and had accumulated 580 hours of service. The manufacturer recommended replacement of the bolts when they had accumulated 500 hours of service, but did not specify a calendar time for replacement. Additionally, there was no regulatory requirement for the owner to follow the manufacturer's recommendations.