The commercial pilot and his passenger were returning to the airport near Tucson, Arizona, after a 30-minute personal flight. The pilot reported he configured the Cessna 310J for landing, but that the landing gear down indication did not illuminate.
He cycled the landing gear several times, but the landing gear down indication still did not illuminate.
After an air traffic controller confirmed that the landing gear was down, he initiated the landing.
The airplane touched down uneventfully, but, about three seconds later, the right main landing gear (MLG) collapsed.
The airplane subsequently veered right and departed the right side of the runway, which resulted in substantial damage to the right aileron and elevator.
A post-accident examination of the landing gear system revealed that the right MLG down-lock tension was about 30 pounds less than the tension prescribed by the airplane’s service manual.
The fork bolt normally used to adjust the down-lock tension was covered in dirt and oil.
Examination also revealed that the MLG nonadjustable drive tube had separated outboard a few inches from a clevis fitting. The signatures on the tube indicated that it failed in compression on the forward/aft plane.
A review of maintenance records revealed that the airplane’s last annual inspection occurred about four months before the accident. The condition of the fork bolt indicates that it had not been adjusted during this inspection.
The pilot also reported that the rigging procedure in the service manual, which included an item to verify the landing gear down-lock brace tension, was not used during any recent inspections.
Maintenance personnel’s failure to perform the rigging procedure during the airplane’s most recent annual inspection likely led to the insufficient down-lock tension and the drive tube’s failure and the subsequent collapse of the right MLG due to the compression forces experienced upon touchdown.
Probable cause: The insufficient right main landing gear (MLG) down-lock tension due to maintenance personnel’s failure to perform a rigging procedure during the airplane’s most recent inspection, which resulted in the right MLG collapsing during landing.
NTSB Identification: WPR16LA015
This October 2015 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.