Incident Overview
After a normal landing, the aircraft rolled through a puddle of water approximately 1 to 2 feet deep while at a speed of 50 to 55 miles per hour during the landing roll. The aircraft decelerated, and at about 35 miles per hour, the right main landing gear began to slowly rotate aft. The aircraft eventually came to rest, supported by the right horizontal stabilizer, the nose gear, and the left main landing gear.
Post-Incident Examination
Examination of the failed landing gear assembly revealed that the attach bolt for the gear spring assembly had failed. This failure allowed the gear to rotate aft. Further inspection of the bolt indicated that it failed due to excessive shear loads placed on it during torsional loading of the upper end of the landing gear tube. Additionally, the bolt showed evidence of fretting. Hardness tests performed on the bolt showed that it was within specifications.
Findings
The bolt's failure was attributed to the excessive shear loads experienced during the torsional loading event. The presence of fretting indicated wear patterns consistent with the loading conditions. The hardness test results confirmed that the bolt met the required specifications, suggesting that the failure was due to the applied loads rather than a material defect.