Hydraulic System Failure
The hydraulic power pack reservoir became depleted due to a leak in the hand pump suction line. The line had been chafed through by interference with the right rudder cable. Despite the leak, sufficient back pressure remained to lower and lock the nose gear, but the main gear did not extend beyond the over-center locks.
Landing Gear Collapse
During the landing roll, the main gear collapsed because it was not fully extended. The landing gear warning horn was improperly rigged and not functional.
Pilot Indication Discrepancy
The pilot stated that he observed a gear-down indication light. However, the indicating system was found to be properly calibrated. According to the system design, a gear-down light could only be displayed if the main gear were fully extended. The pilot’s statement regarding the gear-down indication was in error.