WPR23LA348

After conducting an engine run-up and full-deflection flight control check before the flight, the flight instructor and pilot receiving instruction departed the runway on a local instructional flight in the tailwheel-equipped airplane. Just after takeoff the airplane began to drift right and then suddenly rolled sharply to the right. The airplane’s attitude was held briefly before the flight instructor took over the controls. The flight instructor discovered that the aileron controls were unresponsive. He immediately added left rudder and the wings leveled off. The airplane then started a left roll followed by a right roll. The airplane lost altitude and impacted the ground, resulting in substantial damage to the wings. The pilot reported that the inflight event felt like they were in wake turbulence of a mountain rotor or vortex, or a dust devil. Examination of the airplane’s flight controls did not reveal any anomalies. The reason for the loss of directional control after takeoff could not be determined. Official weather reporting stations in the area showed no significant wind conditions at the time of the accident.

On September 19, 2023, about 0830 mountain standard time, a Champion 7KCAB, N998B, was substantially damaged when it was involved in an accident near Benson, Arizona. The flight instructor and the pilot receiving instruction were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight. The flight instructor reported that he and the pilot were planning to fly about an hour to practice basic maneuvers and then return to the traffic pattern at the Benson Municipal Airport (E95), Benson, Arizona. He reported that the pilot receiving instruction conducted an engine run-up and full-deflection flight control check before the flight. Shortly after departing the runway, while about 50 ft above ground level, the tailwheel equipped airplane began to drift right then suddenly rolled sharply to the right. The airplane’s attitude was held briefly before the flight instructor took over the controls. The flight instructor discovered that the aileron controls were unresponsive. He immediately added left rudder and the wings leveled off. The airplane then started a left roll followed by a right roll. Controlling the airplane’s pitch attitude was normal, but the ailerons did not have any effect on the roll attitude of the airplane. The flight instructor continued to control the airplane with elevator and rudder inputs. The airplane lost altitude and impacted the ground with the wings level. The airplane bounced along the ground and came to rest on the runway. The pilot reported that the inflight event felt like they were in wake turbulence of a mountain rotor or vortex, or a dust devil. A postaccident examination of the airplane’s flight control system revealed aileron control cable continuity and that the ailerons moved freely from the forward and aft cockpit positions. Both aileron bellcranks, pushrods, turnbuckles, pulleys, and cables were examined, and no anomalies were noted. The left aileron bellcrank cover plate was removed. The bellcrank and control stick linkage was intact and operated normally. The right aileron bellcrank and control stick linkage were intact and operated with no restrictions. During the left banking movement of the control stick, the right aileron cable contacted a fuselage longitudinal wood stringer near the aileron bellcrank. The ELT antenna cable was twisted and routed between the right aileron bellcrank and the bellcrank cover plate. The cable was worn on the inboard side and the internal metal cable core was visible. However, there were no restrictions of movement of the bellcrank during the examination. Weather data from the Tucson International Airport (TUS), Automated Surface Observing System, which was located about 50 miles West-Northwest of the accident location, provided wind conditions between 0800 and 0900 that varied between 4 and 6 knots. Longline automated observations from Bisbee Douglas International Airport (DUG), Bisbee, Arizona, which was located about 50 milesSoutheast of the accident location, provided wind conditions between 0556 and 0956 that varied between 3 and 5 knots.