What happened
On July 10, 2012, at approximately 1545 central daylight time, a Maule M-4, registration N12026, underwent a ground loop while landing on runway 3 and at the Springfield Municipal Airport (D42) in Minnesota. The flight, which began at New Ulm Municipal Airport (ULM), involved a private pilot and a flight instructor passenger, both of whom were not injured.
The flight consisted of several segments, including previous landings at Sleepy Eye Municipal Airport (Y58) on a rough grass strip. During the landing at D42, the pilot reported that the touchdown and speed reduction proceeded normally until the tail settled. Upon moving the control yoke from full forward to full aft, the tail of the aircraft abruptly moved to the left. Despite the application of full left rudder and power, the aircraft entered a ground loop to the right, eventually coming to a stop approximately 10 feet off the right side of the runway. The aircraft sustained substantial damage to its left wing.
The investigation
An inspection by a Federal Aviation Administration inspector revealed that one of the three leaf springs in the tailwheel assembly had broken. The pilot noted that this break occurred sometime between takeoff and the conclusion of the accident landing, during a period in which approximately 18 landings had been performed. The inspector determined that the separation in the spring was consistent with overload.