South Africa

The misjudged roundout resulted in a heavy landing which caused the star- board undercarriage to collapse.

The primary cause of the accident was a faulty navigation on part of the Captain of the airplane inasmuch as he set off on an incorrect course and thereafter his visual identification of towns en route was incorrect and based purely on assumptions. Had he checked his assumed ground speed between what he assumed to be Mahalapye and Warmbaths he would have found this to be approximately 318 mph which check would have alerted him. The secondary cause of the accident was the failure of those responsible to alert Pietersburg Aeradio Station and Beacon and the excessive degree of radio interference on the Rand on the evening of 15 September due to electrical storms. The tertiary cause was an attempted landing on a unidentified and unlighted aerodrome, of which the altitude was not known. Thereafter in a low approach the wheels of the airplane struck a rock outcrop approximately 1-1/4 miles from the airfield.

The probable cause of the accident was failure of the port engine caused by the vibration damper bolt partially unscrewing from the roller until the rear damper ring was operating on the bolt shank which eventually failed under excessive loading.

The probable cause of the accident was:
Either:
a) i) Whilst flying in substantially level flight, but momentarily port wing down, the aircraft was subjected to a very severe gust, As a result the weakened engine mounting structure in the port wing gave way, the engine momentarily moving by its inertia towards the right (inwards) relative to the aircraft, It then swung over to the outside and in doing so the propeller cut into the port wing causing severe damage. This damage associated with the conditions at the time caused the wing to collapse.
ii) The aircraft whipped violently over to the left and down- wards resulting in the almost immediate collapse of the tail structure and causing the starboard engine to come out. The propeller of this engine damaged the starboard wing duping its motion away from the aircraft.
iii) The rear end of the fuselage broke away during the violent twisting motion resulting from the failure of the port wing.
Or:
b) Although there would appear to be no very fundamental arguments against the foregoing conception of the cause of the accident, certain members of the Board consider that it does not explain, without somewhat conjectural assumptions, the distribution of the aircraft parts as found on the ground. It also neglects evidence which tends to show that the aeroplane broke up during recovery from a dive. They consider it more probable that it did so, since, it explains more naturally and directly the ground distribution of the aircraft parts. The effect of coming out of a dive would cause both engines to swing to starboard, and tend to cause the whole aircraft to do likewise. If, as a result of this as verified by its ground position, the starboard engine came out first, the effect of this would be that the starboard wing would rise sharply and the port wing correspondingly fall. Some of the port engine supports, being already fractured and weakened by the initial movement towards the starboard side, would then give way due to the weight of the engine now acting in a direction downwards and outwards along the now steeply dipping port wing, Any resulting impact between engine and wing, such as occurred, would accentuate the effect of the gyroscopic torque induced by dive recovery conditions, tending to cause the port wing to break away as it did.