What happened
On 23 May 2025, a Piper PA-28-140 Cherokee, registration ZS-FGU, was conducting a training flight from George Airport to Port Alfred Airport. During a pre-flight inspection at George, the student pilot noted that the engine oil level was low. Following an inspection by a maintenance engineer, approximately two quarts of oil were added to the engine.
While flying near Plettenberg Bay, the pilot observed a decline in oil pressure. Despite the drop in pressure, the oil temperature remained within normal limits, leading the pilot to initially suspect a gauge malfunction. As the aircraft approached the Jeffreys Bay area, the oil pressure continued to drop into the yellow arc, accompanied by abnormal engine noise and vibrations. Eventually, the oil pressure fell to nearly zero.
As the aircraft neared Kenton-on-le-Sea, the engine began running roughly before experiencing a total loss of power. The pilot declared a MAYDAY and, after an unsuccessful attempt to restart the engine, executed a forced landing in a field approximately 6 nautical miles southwest of Port Alfred Airport. The aircraft sustained minor damage, and the pilot escaped without injury.
The investigation
SACAA AIID investigators examined the engine, a Lycoming O-320-E2A, through a detailed teardown inspection. The investigation focused on the sequence of mechanical failures and the oil levels present at departure. Investigators recovered oil cans from the aircraft, noting that only two of the six available cans had been used, suggesting the engine was not topped up to its maximum capacity of eight quarts.
Findings
- The primary cause of the engine failure was progressive oil starvation.
- Internal engine components failed due to a lack of lubrication, specifically involving the failure of a connecting rod on cylinder 4, which breached the engine sump.
- Metallic debris from the initial component failure entered the oil pump, causing the pump to become clogged with metal filings and cease effective oil circulation.
- The pilot did not replenish the oil to the recommended eight-quart level prior to departure, leaving insufficient margin for the flight duration.
- The lack of a corresponding rise in oil temperature during the initial pressure drop likely delayed the pilot's recognition of the actual mechanical failure.