What happened
On November 11, 2011, a Cessna 172M, registration N13584, crashed during a solo instructional flight at Sturgis Municipal Airport (49B) in South Dakota. The flight was being conducted by a student pilot under the supervision of a certified flight instructor (CFI) who was observing the takeoff.
Prior to the accident, the student pilot had completed a second solo landing. According to the CFI, the aircraft's flaps were not retracted following that landing before the subsequent takeoff attempt. During the climbout from runway 29, the aircraft reached a pitch attitude of 60 degrees. The instructor observed the engine producing full power, but the airplane then entered a half-turn spin, resulting in a vertical impact with the terrain south of the runway. The pilot sustained 1 fatal injury.
The investigation
Post-accident examinations of the wreckage were conducted by FAA inspectors and representatives from the aircraft and engine manufacturers. Investigators established flight control continuity, noting only separations caused by impact and overload. The engine was found to be functional, with thumb compression present at all cylinders during crankshaft rotation.
An examination of the flap jackscrew revealed a thread extension of 4.6 inches, indicating the flaps were extended approximately 30 degrees at the time of impact. No mechanical anomalies or pre-impact malfunctions were detected in the airplane or engine.
Toxicology reports conducted by the FAA Civil Aerospace Medical Institute detected acetaminophen and diphenhydramine in the pilot's urine. While diphenhydramine is an antihistamine that can cause drowsiness, investigators could not determine if it played a role in the accident.