N70AC

On July 31, 2013, about 1200 mountain standard time, an experimental amateur built Stribling RV-4, N70AC, sustained substantial damage following a loss of control during takeoff roll, at the San Manuel Airport (E77) San Manuel, Arizona. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. The private pilot, sole occupant of the airplane, sustained minor injuries. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight that was originating at the time of the accident. The pilot's planned destination was Live Oak County Airport (8T6) George West, Texas.

In a written statement to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that during the takeoff roll in the tailwheel equipped airplane, on runway 11 (a 4,207 feet long and 75 feet wide asphalt runway) everything seemed normal until just prior to rotation speed, when the airplane suddenly veered to the left and exited the runway surface. The pilot attempted to correct using rudder, aileron, and elevator control inputs in an effort to get the airplane airborne. Subsequently, the left wing impacted terrain as the airplane traveled down a ravine and nosed over about 420 feet from the runway. The pilot stated that he believed there was nothing wrong with the airplane or the engine.

A witness located at the airport, reported, as the airplane rotated, it veered towards the left and subsequently departed the runway. Another witness, observed the pilot's preceding landing and reported that during the landing roll, the airplane continuously swerved back and forth. The swerves continued in decreasing amplitude until near the end of the 4,207 foot long runway. During a brief discussion with the pilot, the pilot stated to him that the airplane was very sensitive in ground handling.

Examination of the airplane wreckage by a Federal Aviation Administration (FAA) inspector revealed that the fuselage and wings were structurally damaged. The airplane was recovered to a secure location for further examination.

During a postaccident telephone interview with the NTSB IIC, the pilot stated that it was possible that he inadvertently set the stabilizer trim to an improper setting for takeoff but otherwise could not state why the accident occurred. He further stated that when he attempted control inputs to maintain control of the airplane, the airplane felt "mushy," like that experienced in practicing stalls.

Postaccident examination of the airplane by the NTSB IIC revealed no anomalies with the airframe or engine that would have precluded normal operation. The stabilizer trim setting was found near the neutral position and the trim motor operated normally.

The recorded wind at the time of the accident was 180 degrees off runway heading at 5 knots.