What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
N February 22, 2025, the pilot and a passenger departed khef (manassas, VA) at approximately 09:40 et. The aircraft refueled at N94 (carlisle, PA) approximately one hour later before continuing on the flight. The planned route was from kafn (jaffrey, NH) to N87 (trenton robbinsville airport, NJ) for a scheduled annual inspection.
At approximately 16:35, while en route at 4,500 feet MSL, the pilot heard a loud “pop” followed by a change in engine sound. The engine began to surge, with intermittent power loss, but continued to run in a degraded state. The pilot reported the engine anomaly to ATC and confirmed an emergency. The nearest airport, 11N, was approximately 7.3 miles away, and vectors for diversion were received from ATC.
The aircraft continued to experience engine surging, and the boost pump was turned on, though it did not stabilize engine performance. The pilot and passenger had difficulty identifying 11N until nearly overhead, where the pilot identified the runway environment and initiated an approach. The landing was performed on runway 17.
Once on the ground, the engine continued to operate at low power until the throttle was reduced to idle, at which point the engine stopped. The aircraft was secured, and ATC and airport management were notified.
Upon inspection, the pilot reported no significant external damage was visible, though a small amount of oil leakage was found. The oil level had dropped by approximately half a quart during the flight. The aircraft was removed from the runway and left for further investigation. On February 24, 2025, the engine was inspected. The engine was found to have experienced a failure of the exhaust valve in the #3 cylinder, which resulted in substantial damage to both the #3 and #4 cylinders. Metal shards from the #3 cylinder caused damage to the #4 piston and cylinder. The engine is currently awaiting teardown for overhaul.
As the FAA filed it
N FEBRUARY 22, 2025, THE PILOT AND A PASSENGER DEPARTED KHEF (MANASSAS, VA) AT APPROXIMATELY 09:40 ET. THE AIRCRAFT REFUELED AT N94 (CARLISLE, PA) APPROXIMATELY ONE HOUR LATER BEFORE CONTINUING ON THE FLIGHT. THE PLANNED ROUTE WAS FROM KAFN (JAFFREY, NH) TO N87 (TRENTON ROBBINSVILLE AIRPORT, NJ) FOR A SCHEDULED ANNUAL INSPECTION.
AT APPROXIMATELY 16:35, WHILE EN ROUTE AT 4,500 FEET MSL, THE PILOT HEARD A LOUD “POP” FOLLOWED BY A CHANGE IN ENGINE SOUND. THE ENGINE BEGAN TO SURGE, WITH INTERMITTENT POWER LOSS, BUT CONTINUED TO RUN IN A DEGRADED STATE. THE PILOT REPORTED THE ENGINE ANOMALY TO ATC AND CONFIRMED AN EMERGENCY. THE NEAREST AIRPORT, 11N, WAS APPROXIMATELY 7.3 MILES AWAY, AND VECTORS FOR DIVERSION WERE RECEIVED FROM ATC.
THE AIRCRAFT CONTINUED TO EXPERIENCE ENGINE SURGING, AND THE BOOST PUMP WAS TURNED ON, THOUGH IT DID NOT STABILIZE ENGINE PERFORMANCE. THE PILOT AND PASSENGER HAD DIFFICULTY IDENTIFYING 11N UNTIL NEARLY OVERHEAD, WHERE THE PILOT IDENTIFIED THE RUNWAY ENVIRONMENT AND INITIATED AN APPROACH. THE LANDING WAS PERFORMED ON RUNWAY 17.
ONCE ON THE GROUND, THE ENGINE CONTINUED TO OPERATE AT LOW POWER UNTIL THE THROTTLE WAS REDUCED TO IDLE, AT WHICH POINT THE ENGINE STOPPED. THE AIRCRAFT WAS SECURED, AND ATC AND AIRPORT MANAGEMENT WERE NOTIFIED.
UPON INSPECTION, THE PILOT REPORTED NO SIGNIFICANT EXTERNAL DAMAGE WAS VISIBLE, THOUGH A SMALL AMOUNT OF OIL LEAKAGE WAS FOUND. THE OIL LEVEL HAD DROPPED BY APPROXIMATELY HALF A QUART DURING THE FLIGHT. THE AIRCRAFT WAS REMOVED FROM THE RUNWAY AND LEFT FOR FURTHER INVESTIGATION. ON FEBRUARY 24, 2025, THE ENGINE WAS INSPECTED. THE ENGINE WAS FOUND TO HAVE EXPERIENCED A FAILURE OF THE EXHAUST VALVE IN THE #3 CYLINDER, WHICH RESULTED IN SUBSTANTIAL DAMAGE TO BOTH THE #3 AND #4 CYLINDERS. METAL SHARDS FROM THE #3 CYLINDER CAUSED DAMAGE TO THE #4 PISTON AND CYLINDER. THE ENGINE IS CURRENTLY AWAITING TEARDOWN FOR OVERHAUL.