Cessna 170 N9972A accident near Ponca City, Oklahoma

Probable cause

The pilot's loss of directional control during takeoff with a quartering tailwind, which resulted in a runway excursion.

NTSB analysis

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.

Text from the NTSB. Open the NTSB docket for CEN18LA070 for the full record.