The failure of the flaps to operate properly for undetermined reasons during the initial climb and subsequent aborted takeoff. A factor was the collapse of the main landing gear due to an inadequate amount of time for the gear extension process to be completed.

The worn condition of the hydraulic pump gears which resulted in a continuous running pump, subsequent pump motor overheat and eventually the tripping of the pump motor circuit breaker. An additional cause was the pilot's failure to verify that the landing gear were down and locked. A contributing factor was a partially blocked green annunciator light.