Incident Overview
On 22 July 2005 at 0542Z, a Cessna 172 (registration ZS-IVT) operated by an unknown operator was performing circuit training at Grand Central Aerodrome (FAGC). The aircraft had two persons on board: an instructor and a student. The surface wind was 210° at 10 knots, and visibility was greater than 10 km.
Sequence of Events
According to the instructor, after taking off from runway 17, he simulated an engine failure at approximately 500 feet above ground level by closing the throttle and applying carburettor heat to prevent icing. When he attempted to recover from the simulated failure, the engine did not regain power. The crew executed a forced landing in an open field near Gallagher Estate in Midrand (coordinates S026° 00" 370' E028° 07" 984').
Damage and Injuries
There were no injuries to the occupants. The aircraft sustained damage only to the front wheel spat.
Investigation
Post-incident, the fuel system was checked on site and found free of contamination. The engine was ground tested at full power and operated satisfactorily. The aircraft was then flown back to Grand Central without further issues. The last mandatory periodic inspection (MPI) was performed on 27 June 2005 at 9278 total airframe hours, with 76.4 additional hours flown since.
Probable Cause
According to the carburettor icing chart, the engine failed due to carburettor icing. The engine was at idle power when carburettor heat was applied, which is not very effective at that power setting.