Piper PA-31-350 N4098A accident near Portland, Oregon

Probable cause

The failure of company maintenance personnel to install the upper pivot bolt through the pivot hole in the upper end of the landing gear actuating rod, and the company maintenance inspector's inadequate inspection of the work performed.

NTSB analysis

The pilot reported that when he was preparing to land at his destination, he found that the right main landing gear failed to extend. The pilot diverted back to the originating airport. Maintenance personnel discussed the problem with the pilot and various remedial actions were tried without success. The pilot declared an emergency, and landed with the right main gear retracted. During the recovery efforts, the airplane was jacked up in order to extend the right main landing gear, which locked in place. The airplane was then towed to a hangar. Examination revealed that the upper pivot bolt had not been installed through the pivot hole in the upper end of the actuating rod during recent maintenance. The mechanic who did the repair and the inspector who signed off the repair did not detect the discrepancy.

Text from the NTSB. Open the NTSB docket for LAX08LA080 for the full record.