Incident Overview
While the pilot was lowering the landing gear for landing, the left main landing gear door actuator piston separated from its cylinder, resulting in a complete loss of hydraulic fluid. The left main and nose wheels locked down, but the right main wheel remained in a trailing position.
Pilot Actions
The pilot flew for two additional hours attempting various methods to lock the right main wheel down. Eventually, the pilot elected to land with the gear in that configuration.
Landing and Aftermath
During the landing rollout, the airplane departed the runway and sustained substantial damage.
Investigation Findings
Examination of the failed actuator revealed that the snap ring retaining the rod end in the hydraulic cylinder was intact but had separated from its retention groove. No damage was apparent to the snap ring groove itself. The hydraulic cylinder was reassembled and actuation tests were normal with no leaks.
Maintenance History
There was no record of maintenance performed on the actuator in the last eight years.
Laboratory Analysis
Laboratory inspection showed that the groove and cylinder were machined according to specifications. There was a slight deformation of the groove lip, but it could not be determined whether this was pre-existing.