Contaminated fuel possible cause of plane crash

Contaminated fuel may have been the cause of a small plane crash that left a pilot and his passenger seriously injured, a report has found.

The Air Accidents Investigation Branch (AAIB) said the Ikarus C42 FB100 Bravo craft took off on 3 July from Wycombe Air Park, Buckinghamshire, and crashed in a field shortly afterwards.

The plane was destroyed after it suffered a total loss of power which could not be "positively determined".

The report said it was possible the fuel "was not of the correct grade or quality", but since the accident the operator had purchased a bowser to supply its aircraft with UL91 fuel.

The report said nothing abnormal was noted in the pre-flight inspection, the take-off went as planned, but shortly after the engine ran down smoothly and then stopped.

The pilot, 61, who had 898 hours of flying experience, told the airfield radio operator that he planned to land in a field but did not declare a Mayday.

He then focused on landing but collided with trees during the attempted forced landing.

The report said the craft was fuelled on the morning from a jerry can containing premium E5 unleaded petrol, bought from a local petrol station.

"The quantity of fuel could not be verified," the report said.

Shortly after the incident another aircraft operated by the same flying school suffered engine problems but landed on the runway with only minor damage.

All the school's aircraft were examined and three were found to have a jelly-like substance in the carburettor bowls, all fuelled from the same petrol batch.

"The cause of the engine failure was not positively determined although a mechanical failure of the engine was ruled out," the report said.

An assessment of the fuel showed it "may have been of a lower octane number than specified by the engine manufacturer and may have been contaminated with a diesel, light kerosene or jet fuel".

"This would have prevented the fuel from igniting in the engine cylinders when the spark plugs were activated."

The report said the pilot deciding to land in a field he avoided "a stall/spin scenario that may have had worse consequences".

It was possible "the fuel that had been supplied to the aircraft was not of the correct grade or quality to allow normal combustion within the engine".

"The source of the fuel quality issue was not determined."

It said safety actions were taken by the operator who "purchased a bowser to supply its aircraft with UL91 fuel".

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