What happened
During the initial takeoff attempt, the pilot aborted the ground run because the left engine experienced a loss of power. After performing a new run-up, the pilot attempted a second takeoff. Following liftoff, the aircraft performed several banks to the right and left. During each right bank, the cabin door opened.
The pilot continued the takeoff sequence and reached an altitude of 300 feet. At that point, the airplane executed a sudden and steep left turn, resulting in a descent to the level open terrain. The occupants were not injured.
The investigation
Investigators examined the aircraft's right-side cabin door locking mechanism and found it in the unlocked position with the locking pins retracted. Additionally, a torn fuel manifold valve diaphragm was discovered on the left engine.