The flight proceeded normally after departure until about 1114 hours when the pilot noticed a decrease in engine RPM from 2500 to 2300. He opened the throttle but the RPM continued to decrease. As he was unable to restore power to the engine he turned the aircraft towards an open area, that had been overflown a couple of minutes earlier, and set the aircraft up in a glide. The area chosen was the only suitable area available for a landing. The pilot positioned the aircraft to join the downwind leg of the circuit and transmitted a "Mayday" call. As the aircraft was turned onto final approach the pilot spotted a six metre high tree near the intended touchdown point and manoeuvred the aircraft to avoid the tree. At this stage the flaps were selected fully down and the indicated airspeed was 75 knots. The aircraft subsequently floated for a considerable distance before touching down 453 metres after the first available touchdown point. The distance remaining to a fence at the end of the landing area was 309 metres. During the landing roll the right wingtip struck a small tree, as the pilot was attempting to manoeuvre the aircraft clear of an obstruction, and the aircraft was turned to the right. The right wing then struck a second tree which resulted in it being torn from the aircraft and the travel of the aircraft was halted. An inspection of the wreckage found that there had been an internal failure of one muffler which resulted in two of the four engine exhaust outlets being completely blocked.
