NTSB

Probable cause: The pilot/mechanic’s failure to maintain airspeed following a loss of engine power, which resulted in the airplane exceeding its critical angle of attack and experiencing an aerodynamic stall. Also causal was the pilot/mechanic’s failure to service the engine with oil following maintenance, which resulted in the total loss of engine power.

Probable cause: The failure of the landing gear system to either fully retract or extend due to a cracked hydraulic fitting flare, which resulted in the loss of hydraulic pressure.

Probable cause: The pilot’s failure to maintain adequate separation and visual lookout during landing, which resulted in his airplane colliding with the airplane ahead of it on the runway.

Probable cause: The pilot’s failure to retract the landing gear, which resulted in a gear-down water landing and a nose over.

Probable cause: The pilot’s loss of airplane control during initial climb due to an excessively nose-high attitude. Contributing to the accident was the pilot’s failure to properly set the elevator trim before takeoff in accordance with the Before Takeoff checklist.

Probable cause: The pilot’s improper landing flare, which resulted in a hard landing and the left main landing gear wheel separating from the airplane, followed by an aborted landing, and a subsequent ground loop during the follow-on landing.

A failure to use a physical checklist played a significant part in this accident.

Probable cause: The pilot’s failure to maintain clearance from a tree while maneuvering at low altitude.