Event Summary
During taxi for takeoff, the copilot attempted to increase pressure in the landing gear downline. To do so, he placed the landing gear hydraulic handle in the down position. The copilot later stated that he believed he confused the procedure and instead of pushing the gear hydraulic handle down, he pulled up on the landing gear lock handle. This action would have released the gear mechanical locks. Shortly afterward, the left landing gear collapsed. Simultaneously, hydraulic fluid and fumes entered the cockpit.
Investigation Findings
An investigation into the incident revealed that a hydraulic line connected to the pressure gauge had failed due to overpressure. The exact sequence of events leading to the overpressure was not specified in the report, but the failure of the line was identified as the source of the hydraulic fluid and fumes that entered the cockpit. The investigation did not determine whether the copilot's actions directly caused the line failure or if the line failure contributed to the gear collapse, but the two events occurred in close succession.
Corrective Actions
After the incident, the failed hydraulic line was repaired. The system was then tested and operated normally, indicating that the repair restored proper function. No further recommendations or changes were documented in the source.