Piper PA 24-250 N5966P accident near Mesa, Arizona

Probable cause

The failure of the right main landing gear (MLG) transmission mounting bracket coupled with the differential rigging of the two landing gear cables, which prevented the right MLG from moving to the down-and-locked position before landing.

NTSB analysis

The airline transport pilot reported that, during the approach to land, the right main landing gear (MLG) would not extend and lock, and the locked gear-down position would not illuminate. The pilot attempted to manually extend the gear and get it to lock without success. The pilot then conducted a normal landing, and during the rollout, the right MLG collapsed.

Examination of the airplane revealed that the two landing gear cables were rigged slightly differently and that the right bracket that connected the landing gear transmission to the airframe was broken off. Examination of the break with a magnifying glass revealed that it likely had not occurred recently. With the airplane on jacks and the landing gear cables disconnected, the MLG successfully locked down, and the MLG could be manually returned to the "up" position with no restrictions.

The airplane experienced a gear-up landing 13 years before the accident, and it is likely that the differential rigging of the two gear cables had existed since that time and led to the MLG being just on the edge of locking. The broken bracket that connected the MLG transmission to the airframe likely fractured some time before the accident and eventually separated from the airframe. The separation of the right MLG transmission bracket coupled with the differential rigging of the two landing gear cables likely prevented the right MLG from moving over center to the "locked" position and resulted in the gear-up landing.

Text from the NTSB. Open the NTSB docket for WPR14LA368 for the full record.