History of Flight
On 20 January 2020, a Grumman G-164A agricultural aircraft, registration ZS-IRW, departed from Middelburg Aerodrome (FAMB) for a crop-spraying operation over a farm in the Doornkop area. The pilot completed two loads without incident and returned to base for a third load. After takeoff for the third sortie, the first two spray patterns were uneventful. During the initiation of a climb for the third spray pattern at approximately 50 feet above ground level (AGL), the engine lost power and stopped. The pilot immediately dumped the remaining chemical load and executed a forced landing on an open field. The aircraft touched down on soft, muddy terrain, causing the main landing gear to become stuck and the aircraft to nose over, coming to rest inverted. The pilot reported no injuries.
Aircraft and Engine Information
The Grumman G-164A (serial number 984, manufactured in 1972) was powered by a Pratt & Whitney R-1340-AN-1 Wasp radial engine. The total airframe hours at the time of the accident were 9,345.4. The engine had accumulated 555.4 hours since its last overhaul, which had been performed on 25 May 2001. The aircraft had undergone a mandatory periodic inspection on 9 January 2020 at 9,313.7 hours, with no recorded defects. The propeller was a Hamilton STD 12D40/6101A (serial number 89162) with 293.8 hours since overhaul.
Investigation Findings
The investigation determined that the engine failure resulted from a failed impeller bearing and a broken impeller gear, leading to a supercharger malfunction. The engine oil had been changed on 6 January 2020 during the replacement of cylinder number 4; no anomalies were reported. The aircraft was substantially damaged during the landing sequence, but the pilot was not injured.
Injuries and Damage
The pilot, the sole occupant, was not injured. The aircraft sustained substantial damage. No other property damage occurred.