What happened
While entering the traffic pattern at the destination airport, the pilot attempted to extend the landing gear using both normal and alternate methods. During this process, the left main landing gear failed to extend.
The flight departed the traffic pattern and orbited the airport in an attempt to deploy the gear, but these efforts were unsuccessful. The crew subsequently diverted to an airport equipped with Fire Rescue services. After performing a fly-by for emergency services, the pilot climbed to altitude and performed G-loading maneuvers in an attempt to force the gear into position. Despite these maneuvers, the gear remained retracted. The aircraft was ultimately landed with the left main landing gear in the retracted position.
The investigation
An examination of the aircraft revealed that the lugs on the cylinder head of the left main landing gear jack were fractured. A metallurgical examination of these fractured lugs determined that the failure was caused by overstress. No evidence of progressive fatigue or stress corrosion cracking was found.
The cylinder head is a component with a life limit of 5,000 cycles. The failed part had been installed when the aircraft was manufactured and had accumulated 4,751 cycles at the time of the accident landing. Records indicated that the jack attachment and the surrounding area, which require inspection every 600 hours, had been last inspected 348 hours and 299 cycles prior to the event, with no discrepancies noted during that inspection.