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Analysis

Summary

It was likely that, in lowering the right wing while passing the airstrip and golf course, the pilot 'slipped' the aircraft in order to counter the aircraft tendency to turn. However, the period of any uncoordinated flight could not be determined. Although the quantity of fuel in the selected tank exceeded the '1/4 tanks or less' quoted in the Owner's Manual caution about uncoordinated flight, there was still a risk of fuel starvation and engine stoppage with 1/3 tank capacity. Given the absence of any evidence of pre-accident aircraft defects or engine mis-handling, it is possible that the engine failure was due to uncovering of the right fuel tank outlets and introduction of air into the fuel system.

While the previous power loss event was of interest to the investigation the lack of specific information about that event meant that a link with the engine failure could not be established.

The pilot's response to the engine failure was based on a generic procedure that was inconsistent with the in-flight engine restarting procedures produced by the aircraft manufacturer. Although the investigation could not determine the status of the auxiliary fuel pump wiring, the information available indicated that the LO function of the fuel pump was capable of producing significant fuel flow. It was likely that sustained use of the auxiliary fuel pump, instead of the momentary use specified by the engine manufacturer, provided fuel flow that exceeded the engine's requirements and prevented a restart. Had the pilot referred to the fuel flow gauge, he could have ascertained the amount of fuel being supplied to the engine, and responded accordingly. The pilot's lack of awareness of the manufacturer's procedures could be attributed in part to the absence of the applicable placard and procedure card in the aircraft and the absence of training in type-specific emergency procedures.

The pilot delayed the search for a specific landing site until the aircraft had descended to about 750 ft, because he was initially focussing on restarting the engine. This was primarily due to the pilot's perception that the engine failure was similar to the previous engine power loss event and his expectation that the engine would eventually restart. Although the pilot managed to reach a clear area, an earlier diversion to a specific landing area after the engine failure would have reduced the risk of a forced landing in a less favourable location.

The tailwind during the glide approach, and the limited amount of flap extension had a positive effect on the aircraft's glide range. However, those two factors contributed to a relatively higher touchdown speed, which increased the risk of aircraft damage and occupant injury. Due to the prevailing wind conditions and the track to the landing area, a tailwind during landing was unavoidable. The spring-loaded flap switch combined with high pilot workload made it difficult for the pilot to further extend flap in the late stage of the approach.

 
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