Accident Overview
On August 27, 2020, about 1225 eastern daylight time, a Cessna 172P airplane, registration N65645, was substantially damaged when it was involved in an accident near Weston, Florida. The flight instructor and the pilot receiving instruction were not injured. The airplane was being operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.
Sequence of Events
According to the flight instructor, after practicing holding maneuvers over the Everglades, he noticed that the engine oil pressure was "remarkably low," and the engine oil temperature was "a bit high." He took control of the airplane and flew east toward roadways in case a forced landing became necessary. The engine then began to run rough, vibrate, and lost partial power. The instructor determined the airplane would likely not reach the roadways and turned toward Dade Collier Airport (TNT), Ochopee, Florida, which was about 12 miles away. The engine then vibrated "incredibly" and lost all power. The flight instructor was unable to restart the engine and performed a forced landing into vegetation. During landing, the airplane flipped over and sustained substantial damage to the wings and forward lower fuselage.
Post-Accident Examination
Examination of the airplane by a Federal Aviation Administration inspector revealed that a coating of oil was present on most of the underside of the fuselage, and a hole was found in the engine crankcase near the base of one of the cylinders.
Examination of the engine revealed that the Nos. 1 and 3 cylinder connecting rods were fractured near their crankshaft end. The remnants and fracture surfaces of the rods, as well as their respective journals on the crankshaft, were discolored (blackened and bluish surfaces) and smeared, consistent with thermal stress/damage. The No. 4 cylinder connecting rod remained attached to the crankshaft but would not rotate; its crankshaft end was discolored (black and rust colored), consistent with thermal stress. Bearing material was extruded between the rod and the crankshaft lobe. Holes were found in the crankcase near the base of the No. 4 cylinder and on the bottom of each crankcase half. There were no obstructions found in any visible oil passages in the crankshaft. The engine oil pump was undamaged, contained no debris, and operated smoothly.