The Grob G180A business jet prototype that crashed fatally during a demonstration flight in 2006 went out of control when aerodynamic flutter developed in the aircraft's horizontal stabiliser, according to the German accident investigation agency the BFU.
The BFU report explains: "The cause of the accident was that the horizontal stabiliser broke up in flight due to aerodynamic flutter with the result that the aircraft could no longer be controlled." The BFU adds that the cause of the flutter was not established because the aircraft was not fitted with flight recorders.
The aircraft, flown by one pilot, took off in good daylight weather from Grob's base at Mindelheim/Mattsies to carry out a demonstration fly-past for a potential customer. This was a pre-production test aircraft operating on a permit to fly, and the pilot operated within the cleared speeds and loadings.
The BFU recommends that the LBA German aviation authority should require aircraft of more than 5,700kg (12,550lb) on a permit to fly for test flights to be fitted with cockpit voice and flight data recorders, or "an uninterrupted telemetric flight datalink".
This is the second call by a European investigator within a week for business jet types to be fitted with flight recorders. The first was the UK Air Accidents Investigation Branch in its report on the 2008 Cessna Citation 500 crash near Biggin Hill.
Source: Flight International
