Grob says changes on second prototype to improve performance in icing conditions had not been fully tested
When a Grob SPn light twinjet prototype crashed during a demonstration flight on 29 November, both the elevators and the left stabiliser had separated from the aircraft before impact, according to the manufacturer.
Grob's chief test pilot, Gerard Guillaumaud, was flying the second prototype when it crashed 8km (4nm) from the runway while he was lining up for a high-speed pass over the company's Tussenhausen-Mattsies airfield in Germany, according to Grob chief executive Niall Olver. He says there is no doubt separation of the elevators and stabiliser took place, but the reason is so far unknown. Guillaumaud, the aircraft's sole occupant, was killed.
The manufacturer says it had modified the second prototype for better performance in icing conditions, fitting larger ailerons and longer stabilisers, but when the accident took place these modifications had not yet been tested throughout the flight envelope. Grob has now suspended test flying, but is building a third prototype and two production aircraft to join the test programme. It had originally hoped to deliver the type to its first customers in the third quarter of 2007, but is now targeting the fourth quarter.
© Flight International
Grob had lengthened the stabilisers and fitted larger ailerons to the crashed aircraft
The SPn is an all-composite light jet with capacity for up to nine passengers, powered by twin Williams FJ44-3A turbofans, offering short-field performance from gravel or grass strips.