What happened
On 01 March 2018, a Savannah S (registration ZU-KAH) departed Hoedspruit Airfield (FAHT) for a private ferry flight to the SA Wildlife College. Approximately fifteen minutes after takeoff, the aircraft's engine began running roughly before eventually failing completely. Unable to restart the engine, the pilot performed a forced landing in a recently ploughed field at Mokwalo farm. Due to the soft terrain, the nosewheel collapsed during the landing roll, causing the aircraft to nose over and come to rest in an inverted position. The pilot escaped the wreckage without any injuries.
The investigation
SACAA AIID investigators examined the wreckage and conducted a teardown of the engine. The inspection revealed that the engine was equipped with a non-standard Rotax mechanical fuel pump. Within the left-hand carburetor, investigators found a disintegrated retaining clip and a broken fixation screw. A fragment of the broken clip had become lodged in the needle jet, which obstructed the fuel flow. This obstruction created an imbalance in the fuel supply, triggering the engine's rough running and subsequent shutdown.
Findings
- The engine failure was caused by fuel starvation resulting from a failed retaining clip and screw within the carburetor.
- The aircraft had recently completed an 800-hour Mandatory Periodic Inspection (MPI).
- The pilot held a valid license and the aircraft possessed a valid authority to fly.
- While the aircraft was maintained according to manufacturer standards, the Rotax Maintenance Manual specifies that carburetor inspections should occur every 200 hours.
Safety action
- It is recommended that owners and operators of aircraft utilizing Rotax engines ensure strict compliance with the 200-hour carburetor inspection interval.