What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Aircraft departed kapa (denver centennial) airport earlier in the day after undergoing maintenance and flew for approximately 3 hours to kofk (Norfolk regional airport) with no issues noted by the pilot. Pilot landed in the kofk, and stated they added fuel and two quarts of oil, as the pilot felt the oil level was low. Pilot stated they checked under the engine after fueling and no visible leaks were noted. Pilot departed kofk at approximately 20:15Z and began climbing out. At 5900’ MSL, the pilot noticed the oil pressure light on, oil pressure gauge read 0 PSI, and began to experience a loss of power. The pilot immediately turned the aircraft back toward kofk while the engine continued to lose power, and the aircraft landed off-airport in a soybean field. Upon landing, the pilot noticed an engine plug laying in a pool of oil at the bottom of the engine cowling and oil under the aircraft. Pilot stated this plug came from an oil port on the oil sump assembly under lower right front side of the engine. Investigation found the engine plug and plug hole on the engine oil sump assembly both had spots for safety wire, however there was no evidence of either having been previously safety wired. The lack of safety wire allowed the plug to fall out during previously landing or while in-flight.
As the FAA filed it
AIRCRAFT DEPARTED KAPA (DENVER CENTENNIAL) AIRPORT EARLIER IN THE DAY AFTER UNDERGOING MAINTENANCE AND FLEW FOR APPROXIMATELY 3 HOURS TO KOFK (NORFOLK REGIONAL AIRPORT) WITH NO ISSUES NOTED BY THE PILOT. PILOT LANDED IN THE KOFK, AND STATED THEY ADDED FUEL AND TWO QUARTS OF OIL, AS THE PILOT FELT THE OIL LEVEL WAS LOW. PILOT STATED THEY CHECKED UNDER THE ENGINE AFTER FUELING AND NO VISIBLE LEAKS WERE NOTED. PILOT DEPARTED KOFK AT APPROXIMATELY 20:15Z AND BEGAN CLIMBING OUT. AT 5900’ MSL, THE PILOT NOTICED THE OIL PRESSURE LIGHT ON, OIL PRESSURE GAUGE READ 0 PSI, AND BEGAN TO EXPERIENCE A LOSS OF POWER. THE PILOT IMMEDIATELY TURNED THE AIRCRAFT BACK TOWARD KOFK WHILE THE ENGINE CONTINUED TO LOSE POWER, AND THE AIRCRAFT LANDED OFF-AIRPORT IN A SOYBEAN FIELD. UPON LANDING, THE PILOT NOTICED AN ENGINE PLUG LAYING IN A POOL OF OIL AT THE BOTTOM OF THE ENGINE COWLING AND OIL UNDER THE AIRCRAFT. PILOT STATED THIS PLUG CAME FROM AN OIL PORT ON THE OIL SUMP ASSEMBLY UNDER LOWER RIGHT FRONT SIDE OF THE ENGINE. INVESTIGATION FOUND THE ENGINE PLUG AND PLUG HOLE ON THE ENGINE OIL SUMP ASSEMBLY BOTH HAD SPOTS FOR SAFETY WIRE, HOWEVER THERE WAS NO EVIDENCE OF EITHER HAVING BEEN PREVIOUSLY SAFETY WIRED. THE LACK OF SAFETY WIRE ALLOWED THE PLUG TO FALL OUT DURING PREVIOUSLY LANDING OR WHILE IN-FLIGHT.