What happened
On 22 September 2002, a Harvard AT-6D, registration ZU-AYS, was operating as the third aircraft in a three-plane formation. The flight had departed from Runway 19 at Waterkloof Air Force Base with the intention of proceeding to Rand Airport. While climbing through 1,000 feet above ground level, the pilot observed a low fuel pressure warning light, which was immediately followed by a total engine failure.
In an attempt to maintain engine operation, the pilot utilized the auxiliary hand fuel pump; however, this effort failed to restore pressure. Consequently, the pilot performed a forced landing in a rocky field located roughly 2 nautical miles south of the Waterkloof Air Force Base. During the subsequent ground roll, the aircraft veered to the right and traveled approximately 150 meters from the initial point of contact. The aircraft's landing gear struck rocks, leading to the collapse of the left-hand gear and significant structural damage to the propeller, left-hand wing, center section, and both main landing gears. Despite the extensive damage to the aircraft, there were no injuries to the two occupants.
The investigation
Investigators examined the mechanical failure of the engine and the subsequent landing sequence. The inquiry focused on the loss of fuel pressure and the failure of the auxiliary pumping method. Metallurgical analysis was performed on the engine components to determine the origin of the fuel starvation.
Findings
- The engine failure was the direct result of fuel starvation.
- This starvation was caused by the failure of the engine-driven fuel pump drive.
- Metallurgical evidence indicated that the shaft failure resulted from strain loads caused by a combination of torsional loading and shock loads sustained during the period of operation.