What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Pilot departed (eul) caldwell, Idaho in N39998, Cessna 170B with intentions to fly to mccall Idaho. After passing Emmett, Idaho airport the pilot noticed vibrations coming from the engine. The pilot decided to turn around knowing he just passed Emmett, Idaho airport. After performing a 180* turn to head back to the nearest airport the engine started vibrating excessively, a load bang came from the right side of the engine area and a portion of the engine cowling depart the aircraft. The pilot still had control of the aircraft and found a farm field to glide the aircraft to. The aircraft was landed in a field with no additional damage. After exiting the aircraft the pilot observed the right rear cylinder jug depart the engine, but was still laying in the engine compartment.
As the FAA filed it
PILOT DEPARTED (EUL) CALDWELL, IDAHO IN N39998, CESSNA 170B WITH INTENTIONS TO FLY TO MCCALL IDAHO. AFTER PASSING EMMETT, IDAHO AIRPORT THE PILOT NOTICED VIBRATIONS COMING FROM THE ENGINE. THE PILOT DECIDED TO TURN AROUND KNOWING HE JUST PASSED EMMETT, IDAHO AIRPORT. AFTER PERFORMING A 180* TURN TO HEAD BACK TO THE NEAREST AIRPORT THE ENGINE STARTED VIBRATING EXCESSIVELY, A LOAD BANG CAME FROM THE RIGHT SIDE OF THE ENGINE AREA AND A PORTION OF THE ENGINE COWLING DEPART THE AIRCRAFT. THE PILOT STILL HAD CONTROL OF THE AIRCRAFT AND FOUND A FARM FIELD TO GLIDE THE AIRCRAFT TO. THE AIRCRAFT WAS LANDED IN A FIELD WITH NO ADDITIONAL DAMAGE. AFTER EXITING THE AIRCRAFT THE PILOT OBSERVED THE RIGHT REAR CYLINDER JUG DEPART THE ENGINE, BUT WAS STILL LAYING IN THE ENGINE COMPARTMENT.