What happened
On 13 May 2021, a PA-32RT-300T aircraft, registered ZS-CKM, departed Port Elizabeth Aerodrome for Pietermaritzburg Aerodrome under instrument flight rules. The flight, which included a pilot, a co-pilot, and one passenger, proceeded normally until approximately two hours into the journey.
During the cruise phase, the crew experienced loud noises, severe vibrations, and a significant drop in power. Despite attempts to troubleshoot the issue and divert to Margate Aerodrome, the engine eventually ceased functioning entirely. The pilot identified a gravel road in Umtentweni as a suitable site for an emergency landing. During the landing roll, the aircraft's wing tips struck two roadside sign poles, causing the ailerons to detach and the wing tips to be severed. While the aircraft sustained substantial damage, all three occupants escaped without injury.
The investigation
SACAA AIID investigators examined the engine following the accident. Post-accident disassembly and metallurgical testing revealed that the engine's crankshaft had suffered two primary fractures. The analysis determined that these fractures were the result of fatigue in the web section of the crankshaft caused by operational stresses. The investigation also looked into maintenance records, noting that the engine had been in service for over 21 years.
Findings
- The engine lost power and stopped due to the failure of the crankshaft.
- The crankshaft failure was caused by fatigue cracking.
- The crankshaft had not been inspected for wear or condition at the 2000-hour or 12-year intervals as recommended by the manufacturer.
Safety action
- It is recommended that the Director of Civil Aviation review or cancel AIC 18.19, which currently allows private operators to bypass certain manufacturer-mandated engine overhaul calendar requirements.
- A recommendation was made for the manufacturer to expand Airworthiness Directive 2002-19-03 to include all relevant crankshaft and piston engine serial numbers.