Primary finding
Probable cause
The partial failure of the landing gear retraction/extension assembly from restricted hydraulic fluid movement through a partially failed main landing gear uplock release valve.
Investigator assessment
Analysis narrative
After takeoff the pilot moved the landing gear handle to retract the gear. He did not get a gear up light. He then tried the gear down position and no light illuminated. Several flyby's were accomplished and ground personnel informed the pilot that the nose gear was down, the main gear were trailing, and all gear doors were down. The pilot cancelled his original flight plan and refiled VFR. Upon reaching the new destination, he communicated with technical personnel by radio in an effort to correct the malfunction. The airplane was landed approximately 1.5 hours later on runway 18. The main gear remained unlocked and collapsed upon touchdown. Inspection of the airplane revealed the main landing gear uplock release valve had failed. The valve would allow hydraulic pressure to unlock the gear, but would not allow hydraulic fluid to pass through the valve to the main actuators.
Source record
Factual narrative
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