20010203002259A

(-23) I am larry d. enlow, an employee of the federal aviation administration, serving as an aviation safety inspector, assigned to the orlando flight standards district office, orlando, Florida. On February 3, 2001, I investigated an accident, occurring at Sebastian, Florida, involving velocity N658SE, an experimental aircraft. N658SE deaprted sebastain municipal airport at approximately 14:30 local time. This was the first test flight of this experimental aircraft. The pilot stated that after climbing to approximately 2000 feet and accelerating to approximately 135 knots, the left winglet began to flutter. The pilot reduced poswer to slow down, and applied left rudder pressure. The left rudder stopped fluttering, but obtained no response. The aircraft then began an uncommanded right turn. The pilot began a descent and attempted an emergency landing in a field inverted, resulting in substantial damage to the airplane. A post crash investigation revealed that the winglets, and attached rudders, had been improperly manufactured. The winglet rudders operate individually and only move outward to create drag, which yaws the airplane. The trailing edge of the left and right ru dder is designed with a slight outward bend, thus causing the relative wind to apply pressure in the opposite direction of the normal movement of the rudder. Such pressure forces the rudder against its stop, or maintains pressure against the rudder cable during application of rudder control input, and, therefore, prevents flutter. The trailing edge of the and right rudder installed on N658SE were manufactured with a slightly inward bend, thus causing the relative wind to apply pressure in the direction of the normal movement of the rudder. With the being forced outward away form its stop, a classic flight control flutter situation resulted. Although it cannot be determined as a certainty due to impact damage, it appears that the right rudder cable attachement arm was ripped out of the right rudder attach point during flight due to excessive loads imposed by flutter of the right rudder. Such occurrence would explain the uncommanded right turn of the aircraft that continued until impact. According to the pilot, this was first time that the winglets installed on N658SE had ever been used. The winglets were maufactured in brazil by sao francisco plasticos, and installed on the w ing by the owner/builder. Appropriate measures have been taken to locate all winglets manufactured by sao francisco plasticos, so they will not be used on other aircraft. Additional measures will be taken to address quality control issues associated with sao francisco plasticos.