What happened
On 22 May 2021, a Cessna 182L, registration ZS-FIY, departed from Ermelo Aerodrome in Mpumalanga as part of the 2021 President’s Trophy Air Race. The flight, which included the pilot and one passenger, proceeded normally until approximately 15 minutes into the flight. While cruising, the engine began to operate roughly and subsequently lost power, causing the aircraft to descend.
In response to the power loss, the pilot performed an emergency landing on an open field on a farm located near the Arnot Power Station Airfield. While the aircraft sustained minor damage to the right main wheel fairing and the engine's number 5 cylinder, there were no injuries to the occupants.
The investigation
An investigation by the SACAA AIID focused on the mechanical state of the engine and the circumstances leading to the power loss. Investigators examined the engine's maintenance history, noting that the engine had been overhauled in 2003 and had flown over 1,280 hours since that time. The investigation also reviewed the most recent mandatory periodic inspection, which had been completed roughly two months prior to the incident.
Technical analysis of the engine components was conducted following the incident. The remaining five cylinders were subjected to non-destructive testing (NDT), including magnetic particle and fluorescent dye inspections, to identify any further structural issues.
Findings
- The primary cause of the incident was the failure of the rocker shaft boss on the number 5 cylinder.
- This failure was likely caused by metal fatigue, which induced significant vibration and rough engine operation before the total loss of power.
- The pilot successfully adhered to the emergency procedures outlined in the Pilot’s Operating Handbook (POH) during the descent.
- Documentation gaps were noted regarding the specific NDT results from the engine's 2003 overhaul.