What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Cessna 172 N2097T, total time on the engine 6073.8 ? Time since major overhaul ? 3956.2 hrs. Total time on the airframe 10,024 hrs - 46 hrs since the last 100 hr inspection - 704HR since last annual inspection.
The aircraft departed general dewitt spain airport (M01) @ 0730 12/23/2019 for a scheduled training event. Reported weather conditions were partly cloudy with 1800? Ceiling. The first leg of the training event included pattern work within the airspace of M01. At approximately 0815 the pattern work concluded and the student and instructor headed west to practice maneuvers required for a CFI. When they were approximately 20 miles north east of M01 and heading back, they noted a change in engine noise but no power loss. When approximately 10 miles from M01, as the PIC was cancelling flight following, the engine made an explosive noise with debris departing the aircraft and covering the aircraft with oil. The PIC declared an emergency, shutdown the engine and landed safely in the field below.
Inspection revealed the following: the right side cowling had an outwardly forced v-shaped opening at the seam of both lower and upper cowl sections. The #3 cylinder was missing and with the exception of one stud, all cylinder attach studs and thru-studs sheared. The surviving stud was located on the lower aft attach point showing evidence of metal transfer and distorted threads. The upper thru-stud sheared below the housing deck. The lower thru-stud sheared 2 threads above the housing deck and shows a granulated shear lip on the forward 20%. The connecting rod remained attached to the crankshaft. The piston head was found in the lower cowl.
As the FAA filed it
CESSNA 172 N2097T, TOTAL TIME ON THE ENGINE 6073.8 ? TIME SINCE MAJOR OVERHAUL ? 3956.2 HRS. TOTAL TIME ON THE AIRFRAME 10,024 HRS - 46 HRS SINCE THE LAST 100 HR INSPECTION - 704HR SINCE LAST ANNUAL INSPECTION.
THE AIRCRAFT DEPARTED GENERAL DEWITT SPAIN AIRPORT (M01) @ 0730 12/23/2019 FOR A SCHEDULED TRAINING EVENT. REPORTED WEATHER CONDITIONS WERE PARTLY CLOUDY WITH 1800? CEILING. THE FIRST LEG OF THE TRAINING EVENT INCLUDED PATTERN WORK WITHIN THE AIRSPACE OF M01. AT APPROXIMATELY 0815 THE PATTERN WORK CONCLUDED AND THE STUDENT AND INSTRUCTOR HEADED WEST TO PRACTICE MANEUVERS REQUIRED FOR A CFI. WHEN THEY WERE APPROXIMATELY 20 MILES NORTH EAST OF M01 AND HEADING BACK, THEY NOTED A CHANGE IN ENGINE NOISE BUT NO POWER LOSS. WHEN APPROXIMATELY 10 MILES FROM M01, AS THE PIC WAS CANCELLING FLIGHT FOLLOWING, THE ENGINE MADE AN EXPLOSIVE NOISE WITH DEBRIS DEPARTING THE AIRCRAFT AND COVERING THE AIRCRAFT WITH OIL. THE PIC DECLARED AN EMERGENCY, SHUTDOWN THE ENGINE AND LANDED SAFELY IN THE FIELD BELOW.
INSPECTION REVEALED THE FOLLOWING: THE RIGHT SIDE COWLING HAD AN OUTWARDLY FORCED V-SHAPED OPENING AT THE SEAM OF BOTH LOWER AND UPPER COWL SECTIONS. THE #3 CYLINDER WAS MISSING AND WITH THE EXCEPTION OF ONE STUD, ALL CYLINDER ATTACH STUDS AND THRU-STUDS SHEARED. THE SURVIVING STUD WAS LOCATED ON THE LOWER AFT ATTACH POINT SHOWING EVIDENCE OF METAL TRANSFER AND DISTORTED THREADS. THE UPPER THRU-STUD SHEARED BELOW THE HOUSING DECK. THE LOWER THRU-STUD SHEARED 2 THREADS ABOVE THE HOUSING DECK AND SHOWS A GRANULATED SHEAR LIP ON THE FORWARD 20%. THE CONNECTING ROD REMAINED ATTACHED TO THE CRANKSHAFT. THE PISTON HEAD WAS FOUND IN THE LOWER COWL.