What happened
On the afternoon of 8 June 2023, a pilot operating a Micro Aviation SA Bat Hawk R, registration ZU-IXD, departed Letaba Aerodrome for a surveillance flight toward Phalaborwa Aerodrome. The flight was being conducted under visual meteorological conditions in accordance with Part 94 regulations.
Roughly ten minutes after takeoff, while cruising at approximately 500 feet, the pilot noticed a clear liquid dripping onto his shoulder and splashing against the windscreen and left wing. Fearing a fuel leak from the carburettor could ignite upon contact with the hot exhaust, the pilot identified an empty stretch of the S131 gravel road within the Kruger National Park and decided to perform a precautionary landing.
While the landing on the corrugated road surface was initially smooth, the pilot was unable to decelerate sufficiently due to the uneven terrain. At approximately 45 km/h, the right wing of the Bat Hawk R struck a small mopani tree, causing the aircraft to veer off the road and collide with a second tree. The impact resulted in substantial damage to the aircraft. The pilot sustained one injury, consisting of bruises to his left side, and was subsequently treated at a hospital in Phalaborwa.
The investigation
SACAA AIID examined the aircraft and the circumstances surrounding the engine leak. The investigation confirmed that the aircraft was airworthy and had undergone a maintenance inspection shortly before the flight. The pilot was found to be properly licensed and medically fit.
Upon inspecting the aircraft after the crash, the pilot noted that the leaking liquid smelled more like a watery oil than fuel. Investigators identified that the drain plug on the engine's oil breather container was missing. This container is located on the left side of the Rotax 912 ULS engine.
Findings
- The primary cause of the accident was a liquid leak from the engine that prompted an unsuccessful precautionary landing, leading to the tree collision.
- The missing drain plug on the oil breather container was the contributing factor; it lacked a locking mechanism and likely vibrated loose during flight, allowing oil-based liquid to escape.
- The corrugated nature of the gravel road prevented the pilot from slowing the aircraft quickly enough to avoid the obstacle.