Investigators Say Flutter Might Have Felled Grob SPn

Initial findings from German aviation authorities on the crash of a Grob Aerospace SPn Utility Jet prototype say flutter might have played a role in the Nov. 29, 2006 accident. According to a report from the manufacturer, the German Federal Bureau of Air Accident Investigation said that parts of the twinjet’s tail control surfaces were found some 1,300 feet from the impact site, indicating the aircraft shed them in flight. This aircraft, the second prototype, had recently had the elevators and horizontal stabilizer enlarged, based on data from flight tests of the first test SPn. The report says the airplane was approaching the manufacturer’s private airport in southern Germany, intending to make a high-speed pass with the landing gear retracted, when it crashed, killing chief test pilot Gerard Guillaumaud. Investigators are now focusing on determining the SPn’s speed at the time of the crash, to see if it exceeded the prototype’s permitted speed envelope.