What happened
On the morning of 27 April 2022, a Jabiru SP aircraft, registration ZU-CIA, departed Rhino Park Aerodrome in Gauteng for a private flight to Witbank Aerodrome. While cruising at 6,500 feet, the aircraft's engine suddenly faltered and ceased operation. Despite the pilot's attempts to restart the engine using the auxiliary fuel pump and carburettor heat, the engine remained non-functional.
Seeking a safe landing site away from heavy traffic on the nearby N4 highway, the pilot identified a clear section of the R10 and executed a forced landing on the provincial roadway. While the landing itself was successful, the outer edge of the left wing struck a road sign pole during the landing roll. This impact caused the aircraft to veer off the road and skid onto the gravel, where the right main landing gear support strut detached. The aircraft eventually came to rest on its right wing. There were no injuries to the pilot or the passenger.
The investigation
SACAA AIID investigators examined the wreckage and performed a teardown inspection of the engine. The investigation focused on why the engine failed despite the engine being well within its service limits, having completed only 412.7 hours since its last overhaul. Laboratory analysis of the crankshaft gear was conducted to identify the source of the mechanical failure.
Findings
- The primary cause of the in-flight engine stoppage was the failure of the crankshaft gear.
- Metallurgical examination determined that the gear failure was caused by hydrogen embrittlement, a condition likely introduced during the manufacturing process of the gear assembly.
- The pilot successfully identified a suitable landing area on the R104 with no oncoming traffic.
- The secondary damage to the airframe, including substantial damage to the wing and landing gear, was caused by the collision with a road sign pole during the landing roll.