What happened
On 7 November 2009, a Piper PA28-180 Cherokee Archer, registration ZS-FBE, departed from Potchef and was en route to Kroonstad for a private flight. Shortly after the aircraft reached 500 feet above ground level and began a turn, the engine started running roughly.
Suspecting carburettor icing, the pilot activated the carburettor heat. However, this action caused the engine to lose power even more rapidly. After the pilot deactivated the carburettor heat, the engine ceased operating entirely. The pilot attempted a restart but was unable to do so, necessitating a forced landing in an open stretch of veld. During the landing, the nose gear struck a rock and collapsed, and the propeller made contact with the ground. There were no injuries to the pilot or the passenger.
The investigation
SACAA AIID investigators examined the aircraft and the circumstances surrounding the engine failure. Post-accident testing of the Lycoming engine revealed no mechanical defects, confirming the engine was serviceable at the time of the incident. The investigation also noted that the aircraft had been imported from Namibia, and while the airframe maintenance was properly certified, there were no prior logbook entries regarding the specific propeller installation.
Findings
- The pilot was properly licensed and qualified for the operation.
- The aircraft was airworthy and maintained by an approved organization.
- The pilot had set the air-fuel mixture too lean during pre-takeoff checks and throughout the takeoff phase.
- The application of carburettor heat to the air intake system further enriched the air-to-fuel ratio in a way that made the already lean mixture too lean to sustain combustion, leading to the engine stoppage.
- The nose gear failure was caused by the impact with a rock during the landing sequence.