DEN06LA100 · Maule M 6 180C

In the fall of 2004, the airplane had been damaged while in a hangar during a hurricane. During the repairs, the wings were removed and reinstalled. Prior to the pilot's purchase of the airplane, he and an inspection authorization (IA) certificated mechanic examined the airplane and the airplane's maintenance records. During the cross-country flight back to the pilot's state of residence, he landed for an intermediate fuel stop. After refueling, the pilot taxied to runway 34 for takeoff. According to the airport's automated weather observing system (AWOS), the density altitude was 10,300 feet mean sea level and the wind was 4 knots from the west. In accordance with the airplane flight manual, the pilot selected the second notch of flaps (24 degrees) for the takeoff. During the takeoff roll, the airplane began to "lift off (feel light) and the tail wheel left the ground, the [airplane] began turning left." The pilot attempted to maneuver the airplane back to the runway centerline; however, the application of "right rudder was ineffective." The airplane's main landing gear struck a runway light and the airplane was approaching a snow fence. Subsequently, the pilot "intentionally ground-looped the airplane," and the airplane came to rest upright in a field adjacent to the runway. Examination of the airplane revealed that the wing flap system was not rigged in accordance with the airplane's maintenance manual. The accident airplane's "handle full down" flap setting was 0 degrees, and according to the manual, the "handle full down" flap setting was negative 7 degrees. The flap settings were found to be misrigged by 7 degrees through the entire flap setting range. In accordance with the airplane flight manual, the flap handle position for takeoff should be set the second notch, or 24 degrees of flaps, position. Due to the improperly rigged flap setting, the actual flap position during the accident attempted takeoff was 31 degrees. According to the airplane manufacturer, the 31 degrees of flaps at takeoff would produce increased drag and premature lift of the wing. During takeoff with the improper flap position, elevator authority would be available; however, rudder authority may be decreased at lower airspeeds.

Verbatim NTSB analysis and probable cause from the NTSB dataset