The pilot had altered the mixture setting on each engine’s carburettor and decided to carry out a short flight to check the adjustments. The weather was good, with a light wind, CAVOK, OAT 29°C, dew point 16°C and a QNH of 1008 hPa. He flew a circuit from Runway 03 during which both engines seemed to run normally. He then turned the aircraft onto final approach and lowered landing flap, whilst still retaining a moderate power setting. At a speed of approximately 60 KIAS and at a height of 400 to 500 ft agl, he closed one throttle followed by the second. As he closed the second throttle, the first engine stopped. He started to advance the throttle of the live engine but this also stopped. The nose pitched down and he established a glide approach. During the flare, at about two feet, the right wing dropped and the aircraft sank onto the grass surface, landing heavily. During the touchdown, the pilot’s head struck the canopy but he was uninjured.
The pilot considered that the engines had stopped due to the adjustment of the mixture controls on both carburettors, giving excessively lean conditions at low RPM whilst in flight.