What happened
On 13 June 2003, a Jabiru J400, registration ZU-ZAN, departed from Grand Central Aerodrome (FAGC) for a training session. The flight was being conducted by a pilot accompanied by a student pilot, who was undergoing conversion training on the aircraft. The flight path was intended to cover the Pretoria GF1 area before returning to Grand Central.
During the flight, the crew performed a series of incipient spins followed by a stall. Immediately after recovering from the stall, the engine began running roughly. Recognizing the deteriorating engine performance, the pilot opted to perform a precautionary landing at an abandoned airfield located in the Kameeldrift area (S 25˚46’ E028˚04’). Weather conditions at the time were clear, with calm winds and a temperature of 20˚C.
The investigation
SACAA AIID investigators examined the engine and the aircraft's maintenance history. The investigation established that the engine experienced a substantial loss of power due to a mechanical failure within the engine assembly. Additionally, investigators reviewed the aircraft's logbook entries regarding required maintenance intervals.
Findings
- The primary cause of the engine malfunction was that the exhaust valve seat on the number 2 cylinder became dislodged.
- This mechanical failure resulted in a significant reduction in engine power.
- There was no evidence in the aircraft logbook to confirm that required maintenance tasks had been completed. Specifically, the maintenance manual requires checking tappet clearances and cylinder head bolt torque every 5 hours during the initial 15 hours of operation; no records indicated compliance with these instructions.
Safety action
No specific safety recommendations were recorded in the provided report.