What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) According to the instructor, he was demonstrating slow flight to his student. During the process, he was going to demonstrate an approach to landing stall. The instructor stated when he reduced power, the propeller seemed to be turning slowly. When he applied power, "nothing happened", and the propeller stopped rotating. He stated he lowered the nose of the aircraft, and noticed the electrical instruments flash off and on, he also stated he attempted to restart using the starter but the propeller did not turn. Investigation of the engine by airworthiness inspectors revealed nothing unusual, there was free rotation of the propeller, fuel was present as well as spark. Compression tested good, and the alternator was not binding. The aircraft was at three thousand feet when the engine stopped. The instructor chose a rough, partially plowed field, touched down slowly but the aircraft nosed over on its back breaking two of the engine mounts and buckled the wing spars. The propeller blades were bent towards the rear of the aircraft, and there was no sign of engine power on the leading edge of the propeller. The weater was VMC, there were only minor injuries.
As the FAA filed it
(-23) ACCORDING TO THE INSTRUCTOR, HE WAS DEMONSTRATING SLOW FLIGHT TO HIS STUDENT. DURING THE PROCESS, HE WAS GOING TO DEMONSTRATE AN APPROACH TO LANDING STALL. THE INSTRUCTOR STATED WHEN HE REDUCED POWER, THE PROPELLER SEEMED TO BE TURNING SLOWLY. WHEN HE APPLIED POWER, "NOTHING HAPPENED", AND THE PROPELLER STOPPED ROTATING. HE STATED HE LOWERED THE NOSE OF THE AIRCRAFT, AND NOTICED THE ELECTRICAL INSTRUMENTS FLASH OFF AND ON, HE ALSO STATED HE ATTEMPTED TO RESTART USING THE STARTER BUT THE PROPELLER DID NOT TURN. INVESTIGATION OF THE ENGINE BY AIRWORTHINESS INSPECTORS REVEALED NOTHING UNUSUAL, THERE WAS FREE ROTATION OF THE PROPELLER, FUEL WAS PRESENT AS WELL AS SPARK. COMPRESSION TESTED GOOD, AND THE ALTERNATOR WAS NOT BINDING. THE AIRCRAFT WAS AT THREE THOUSAND FEET WHEN THE ENGINE STOPPED. THE INSTRUCTOR CHOSE A ROUGH, PARTIALLY PLOWED FIELD, TOUCHED DOWN SLOWLY BUT THE AIRCRAFT NOSED OVER ON ITS BACK BREAKING TWO OF THE ENGINE MOUNTS AND BUCKLED THE WING SPARS. THE PROPELLER BLADES WERE BENT TOWARDS THE REAR OF THE AIRCRAFT, AND THERE WAS NO SIGN OF ENGINE POWER ON THE LEADING EDGE OF THE PROPELLER. THE WEATER WAS VMC, THERE WERE ONLY MINOR INJURIES.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.