What happened
On 29 July 2011, a Bantam B22J, registration ZU-FHN, was conducting an aerial survey flight near Shingwedzi Aerodrome within the Kruger National Park. The flight, operated by the South African National Parks Board, was being flown by two experienced pilots. Approximately one hour into the mission, the crew observed the oil pressure dropping into the yellow arc on the instrument panel and noticed oil leaking from the left side of the engine.
Following the aircraft's emergency procedures for low oil pressure, the crew decided to perform a precautionary landing to prevent engine seizure. They targeted a stretch of young mopani bush for the touchdown. During the landing roll, the aircraft struck a termite mound that was hidden beneath the vegetation. The impact caused the nosegear to collapse and the engine to shift forward onto the nose cowling, which obscured the pilots' forward vision. The aircraft came to rest in a nose-down position. There were no injuries to the two crew members.
The investigation
SACAA AIID investigators examined the maintenance history and the circumstances leading to the engine failure. The investigation established that prior to the flight, a mandatory five-hour cylinder head torque procedure had been performed on the Jabiru 3300A engine in accordance with Service Bulletin SL8. This maintenance was carried out by the co-pilot, who was also a certified Approved Person (AP).
Investigators found that during the maintenance task, the technician's attention had been diverted because the aircraft needed to be moved out of the hangar to facilitate refueling. Consequently, the bolts on the number six rocker cover were not properly tightened. This oversight led to the oil leak observed during flight.