Cessna 172M Forced Landing on Moloto Road After Engine Failure (ZS-SBN)

Incident Overview and Flight Details On 6 April 2022, a Cessna 172M Skyhawk with registration ZS-SBN was conducting a night-rating training flight under Part 141 of the Civil Aviation Regulations. The aircraft departed Wonderboom Aerodrome (FAWB) in Gauteng Province at 1734Z from Runway 29, carrying a flight instructor and a student pilot. The flight was intended to proceed to the Pretoria general flying area before returning to FAWB. The aircraft was fueled with 120 litres of Avgas 100LL and had no outstanding defects recorded in its flight folio prior to departure. ## Engine Failure and Forced Landing Approximately 15 minutes into the flight, while overhead Rooiwal Power Station at around 6,000 feet, the flight instructor observed a high engine oil temperature indication. He took control of the aircraft and initiated a precautionary turn back toward FAWB. After flying over the N1 Highway, the instructor heard a clicking noise from the engine compartment, which was followed by engine stoppage. The instructor switched on the landing light and glided the aircraft toward Moloto Road, which was clear of traffic. He executed a successful forced landing in a southerly direction on the road. The aircraft sustained minor damage to the right wing tip rear section when a passing truck contacted it before the aircraft was moved to the grass-covered left side of the road. Both occupants disembarked without injury, and no third-party damages were reported. ## Post-Incident Examination and Maintenance History The Lycoming O-320E2D engine (Serial Number L810239A) was removed for a teardown inspection on 7 April 2022 at a South African Civil Aviation Authority-approved maintenance organisation. The inspection revealed that the crankshaft had fractured at the No. 4 connecting rod journal due to fatigue cracking. The broken crankshaft had shifted to the rear of the engine and broken the idler gear between the camshaft and crankshaft. The engine oil level was adequate, and no oil leaks were found. The engine had been overhauled on 13 July 2021 with the same crankshaft, and the failure occurred with 78% of its 2,000-hour time between overhaul remaining. A non-destructive magnetic particle inspection conducted on 3 May 2021 had not detected any cracks. The aircraft had approximately 51 start/stop cycles since that inspection, and fatigue crack growth was estimated to have occurred over at least that period. The aircraft's last pre-incident inspection was a 50-hour oil inspection on 28 March 2022, after which it was issued a Certificate of Release to Service.