Test

Examination of the aircraft disclosed that it was equipped with a front belly tank in addition to the normal wing tanks and that the placard plate for fuel tank selection gave no indication that a belly tank was installed. Examination of the fuel lines and selector valve established that when the selector in the cockpit indicated 'both on', the selector was on the belly tank. A few days before the accident, 5 gallons of gasoline was put in the belly tank when testing the tanks for leaks. It was established that no further fuel was put in the belly tank before the accident although the wing tanks were filled. The aircraft was test flown on 8 May, and fuel was used from all three tanks. On the last flight of the aircraft on 8 May, fuel was used from the belly tank only. It was established that the pilot was not aware that the aircraft was fitted with a belly tank and that in selecting 'both on' he believed that he had selected both wing tanks. Examination of the belly tank after the accident showed it to be empty and undamaged. There was no evidence of failure or malfunctioning of the airframe, engine or controls. Weather was not considered as a factor in the accident. In conclusion, after an emergency forced landing caused by the exhaustion of fuel from the belly tanks the aircraft hit obstructions on the shore line. A contributing factor is considered to have been misleading information given by the placard on the fuel selector valve.

The accident was caused by a collision with trees and the airplane was banking substantially to the left. The cause of this could not be specified due to lack of evidence due to the destruction of the wreck. Certain facts for which a specific explanation could not be found were:
- Extension of the duration of the flight,
- Radio silence,
- Stopping of engine number four,
- Pitch of the propeller on engine three.
Above all these findings, it was established that the crew was flying at low height few minutes before the accident according to the testimony of farmer. The reason for this could not be determined with certainty.

Failure of the right engine just after takeoff.

Study of the flight conditions and circumstances of the accident to the aircraft revealed no mechanical defect which might have been the initial cause of the accident. The cause would appear to have been an abnormal flight maneuver made when the crew experienced difficulty in resuming normal flight on two engines. Overspeed, reduction of pitch or difficulty in re-starting the engine may have created a dangerous situation and caused the aircraft to stall in dissymmetrical flight, thus subjecting the airframe to stresses accompanied by buffeting which was either alternating or exceeded the design limits of the structure and caused the tail-plane to break off.

Engine failure.