CEN18LA070

The pilot departed with a quartering tailwind in a tailwheel-equipped airplane. During the takeoff roll, the airplane veered left; the pilot reported that he applied rudder to stop the turn, but the airplane continued to veer left. As the airplane exited the left side of the runway, the right main landing gear separated from the airplane, and the fuselage and right wing sustained substantial damage. Examination revealed that the main landing gear fracture surfaces were consistent with an initiating fatigue fracture that propagated toward an overstress fracture; the size of the fatigue crack before the final overstress fracture could not be determined. It is likely that the pilot lost control of the airplane during takeoff in a quartering tailwind.

On January 6, 2018, about 1100 central standard time, a Cessna 170A airplane, N9972A, was substantially damaged when it was involved in an accident near Ponca City, Oklahoma. The pilot and three passengers were not injured. The airplane was operated by a private individual as a Title 14 Code of Federal Regulations Part 91 personal flight.The pilot stated that prior to takeoff he observed that the windsock indicated a direct crosswind. He began a takeoff roll on runway 35. On takeoff the airplane began to veer left. The pilot added that he applied rudder to correct for the airplane's left turn. However, the airplane continued to veer left and as it approached the side of the runway, the pilot reduced power. As the airplane exited the side of the runway, the right main landing gear separated from the airplane. The airplane came to rest in the grass off the runway surface. Substantial damage was sustained to the fuselage and right wing spar A review of wind conditions, about the time of the accident, found the wind was reported as 100° at 10 knots. The landing gear was photo documented by the Federal Aviation Administration. Photos were examined by the NTSB Materials Laboratory and discovered that the fracture surfaces were consistent with an initiating fatigue fracture which propagated towards an overstress fracture. The pilot reported having over 100 hours in tailwheel equipped airplanes.