Accident Details
At 1430 hours, an aircraft carrying 10 passengers and a crew of 2 took off from Margate to fly to Rand Airport in Germiston, with a planned stop at Ladysmith. The weather at take-off was overcast with intermittent drizzle; the cloud base was approximately 1,000 feet above the airfield, which is near sea level. The wind was southerly at 20 to 25 knots. Inland, in the direction of flight, the weather appeared as dark rain clouds. The pilot did not receive a meteorological report for the flight before departure.
At 1444 hours, the operator at Durban Airfield received a weak call-sign from the aircraft. However, due to another aircraft in the circuit area, wireless contact was lost completely. At about 1450 hours, people on the ground near Ixopo observed pieces of aircraft falling from the cloud. The aircraft had disintegrated in the air, on course and at a point 49 miles from Margate. All occupants sustained fatal injuries.
Probable Cause
The official findings presented two alternative probable causes:
Alternative (a): While flying in substantially level flight but momentarily with the port wing low, the aircraft encountered a very severe gust. This caused the weakened engine mounting structure in the port wing to give way. The engine momentarily moved inward by inertia relative to the aircraft, then swung outward, causing the propeller to cut into the port wing. This damage, combined with prevailing conditions, led to the wing’s collapse. The aircraft then whipped violently left and downward, resulting in near-immediate collapse of the tail structure and dislodging the starboard engine. The starboard propeller damaged the starboard wing as the engine moved away. The rear fuselage broke away during the violent twisting motion from the port wing failure.
Alternative (b): Some Board members considered that the first conception did not explain the ground distribution of aircraft parts without conjectural assumptions, and neglected evidence suggesting the breakup occurred during recovery from a dive. They found it more probable that recovery from a dive caused both engines to swing to starboard, with the starboard engine coming out first. This would cause the starboard wing to rise sharply and the port wing to drop. The port engine’s supports, already fractured and weakened by initial movement starboard, would give way due to the engine’s weight acting downward and outward along the steeply dipping port wing. Any resulting impact between engine and wing accentuated gyroscopic torque induced by dive recovery, causing the port wing to break away.