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Italian authorities have released the AW609 tiltrotor prototype that was seized as part of their investigation into last year’s fatal crash of the model.
According to manufacturer Leonardo-Finmeccanica, following a recent decision taken by the relevant legal authority in Italy, the company has been able to resume development and testing work on the third prototype of the AW609 tiltrotor at its plant based in Cascina Costa. The aircraft was impounded in May 2016, shortly after its initial ground runs, by Italian prosecutors investigating the crash of the second AW609 prototype during high speed trials on Oct. 20, 2015.
In an interim statement released last month, Italy’s National Agency for Flight Safety (ANSV) reported that the accident aircraft experienced a kind of “augmented Dutch roll” while diving to an extreme maximum speed of 293 knots as part of the flight testing required for certification. The resulting oscillations appear to have led to a catastrophic in-flight breakup, resulting in the deaths of test pilots Pietro Venanzi and Herb Moran.
The accident flight was the first time the aircraft had reached a maximum dive speed of 293 knots with rear fuselage and tail fin modifications that were introduced in 2013 to reduce drag and enhance performance. Noting that the aircraft’s behavior at high speed was not completely predicted by the manufacturer, the ANSV recommended further review of the AW609’s aerodynamic behavior at high speeds, as well as a review of the model’s fly-by-wire flight control laws to ensure the effectiveness of pilot inputs.