Accident Overview
During approach to the airport, the flight crew extended the landing gear, but the gear failed to lock in the down position. Multiple attempts using both the normal and emergency extension systems did not resolve the issue. The instructor subsequently decided to land with the gear retracted, resulting in a gear-up landing.
Component Failure
Post-accident examination revealed that the roller piston (part number 1281019-1) and bearing (part number S1997C7-8) had fallen out of their assembly. This allowed the actuator piston assembly to reindex itself on the main gear pivot assembly, which prevented the left main gear from achieving a locked-down position.
Landing Gear System
The aircraft was equipped with a landing gear extension system that included normal and emergency extension capabilities. Despite several attempts, neither system could rectify the failure. The decision to land with the gear retracted was made after all corrective actions were exhausted.
Examination Findings
The investigation focused on the left main landing gear assembly. The dislodged roller piston and bearing were identified as the cause of the malfunction. The actuator piston assembly's reindexing on the main gear pivot assembly physically blocked the gear from locking down.
Outcome
The aircraft landed with the landing gear retracted. The specific damage to the aircraft was not detailed in the source material. No information regarding occupants, injuries, or operational conditions (such as time of day or weather) was provided.