A missing rivet head may have led to an inadvertent shutdown of an engine of an executive jet which crashed into a house, killing all five people on board, according to an accident report.
About 70 seconds before the Cessna Citation 500 aircraft crashed neither engine was producing any thrust, the report from the Air Accidents Investigation Branch (AAIB) said.
Just before impact, the co-pilot of the aircraft, whose passengers included former British Touring Car Championship driver David Leslie, 54, transmitted: "We have a major problem, a major problem it looks as though we're, er, going in, we're going in."
Also killed were Apex Motorsport boss Richard Lloyd, 63; Christopher Allarton, 25; and pilots Mike Roberts, 63, and Michael Chapman, 57. The aircraft hit a house in Romsey Close, Farnborough, Kent, on the afternoon of March 30 2008 - causing a fire which destroyed the property.
The house owner Edwin Harman, now 74, was away on holiday while his wife, Pat, now 70, had returned from holiday before her husband and was heading home at the time of the accident after spending the night at the home of her daughter.
The garage of a neighbouring house and a car parked next to it were also destroyed by the impact and ensuing fire. But no-one on the ground was injured.
The report said the aircraft had departed from Biggin Hill airport in Kent bound for Pau in south-west France. The AAIB said it was not possible to ascertain the exact role of each pilot during the flight and therefore for the purposes of the report the 57-year-old pilot, which would have been Mr Chapman, was the captain, making Mr Roberts the co-pilot.
One minute into the flight Mr Roberts transmitted a message saying they were making an immediate return to Biggin Hill.
The report said it was probable that a mechanical failure within the air cycle machine - part of the mechanism which helps with cabin ventilation - caused the vibration which led the crew to try to return to Biggin Hill. The AAIB said a rivet head securing the left engine fuel cut-off lever had become detached at some time prior to the crash.
This missing rivet head "may have led to an inadvertent shutdown of that (left-side) engine," the AAIB said. The report said an attempt to relight the second engine "was probably started before the relit first engine had reached idle speed, resulting in insufficient time for enough thrust to be developed to arrest the aircraft's rate of descent before ground impact".