What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
On March 21, 2026 at ~1500 MST, the subject aircraft departed south valley regional airport (U42) heading west over the great salt lake. After ascending over the mountains west of the lake, the PIC began the return flight back to U42. During descent at ~5800 feet elevation, the PIC noticed the rpms drop from 2300 to 2100. The PIC advanced the throttle and manipulated the mixture and fuel selectors; however, the rpms continued to decline. They radioed the emergency over CTAF and with rpms continuing to drop, decided to land the aircraft in a field ~5 miles north west of U42.
Examination of the aircraft after recovery showed impact damage separated the nose landing gear and fractured the lower engine mount near the firewall. Flight control continuity was established to the flight control surfaces. Throttle and mixture control cable continuity was established to their respective components.
During engine examination, rotational continuity was established; however, while rotating the crankshaft there was an unusual amount of resistance noted indicative of an internal mechanical malfunction. The oil filter element contained a large amount of nonferrous debris. The oil filler tube was intact with the cap secured and the dip stick revealed a quantity of ~6 quarts.
The no. 1 cylinder was inspected and found to be unremarkable.
The no. 2 cylinder forward-facing piston pin bushing was worn into a small aluminum ball consistent with long-term abnormal wear. The piston pin bore hold was elongated to the point of interfering with the ring lands of the oil control and second compression ring.
The no. 3 cylinder bearing appeared to have plasticized deformation and was observed partially extruded from the crank shaft journal and connecting rod, consistent with severe lubrication depravation heat distress.
The no. 4 cylinder bearing appeared to have plasticized deformation and was observed partially extruded from the crank shaft journal and connecting rod, consistent with severe lubrication depravation heat distress.
Indications of mechanical failure due to lubrication deprivation are consistent with a loss of engine RPM. Specific component or system failure is still being investigated by NTSB and this report will be amended after that determination has been made.
As the FAA filed it
ON MARCH 21, 2026 AT ~1500 MST, THE SUBJECT AIRCRAFT DEPARTED SOUTH VALLEY REGIONAL AIRPORT (U42) HEADING WEST OVER THE GREAT SALT LAKE. AFTER ASCENDING OVER THE MOUNTAINS WEST OF THE LAKE, THE PIC BEGAN THE RETURN FLIGHT BACK TO U42. DURING DESCENT AT ~5800 FEET ELEVATION, THE PIC NOTICED THE RPMS DROP FROM 2300 TO 2100. THE PIC ADVANCED THE THROTTLE AND MANIPULATED THE MIXTURE AND FUEL SELECTORS; HOWEVER, THE RPMS CONTINUED TO DECLINE. THEY RADIOED THE EMERGENCY OVER CTAF AND WITH RPMS CONTINUING TO DROP, DECIDED TO LAND THE AIRCRAFT IN A FIELD ~5 MILES NORTH WEST OF U42.
EXAMINATION OF THE AIRCRAFT AFTER RECOVERY SHOWED IMPACT DAMAGE SEPARATED THE NOSE LANDING GEAR AND FRACTURED THE LOWER ENGINE MOUNT NEAR THE FIREWALL. FLIGHT CONTROL CONTINUITY WAS ESTABLISHED TO THE FLIGHT CONTROL SURFACES. THROTTLE AND MIXTURE CONTROL CABLE CONTINUITY WAS ESTABLISHED TO THEIR RESPECTIVE COMPONENTS.
DURING ENGINE EXAMINATION, ROTATIONAL CONTINUITY WAS ESTABLISHED; HOWEVER, WHILE ROTATING THE CRANKSHAFT THERE WAS AN UNUSUAL AMOUNT OF RESISTANCE NOTED INDICATIVE OF AN INTERNAL MECHANICAL MALFUNCTION. THE OIL FILTER ELEMENT CONTAINED A LARGE AMOUNT OF NONFERROUS DEBRIS. THE OIL FILLER TUBE WAS INTACT WITH THE CAP SECURED AND THE DIP STICK REVEALED A QUANTITY OF ~6 QUARTS.
THE NO. 1 CYLINDER WAS INSPECTED AND FOUND TO BE UNREMARKABLE.
THE NO. 2 CYLINDER FORWARD-FACING PISTON PIN BUSHING WAS WORN INTO A SMALL ALUMINUM BALL CONSISTENT WITH LONG-TERM ABNORMAL WEAR. THE PISTON PIN BORE HOLD WAS ELONGATED TO THE POINT OF INTERFERING WITH THE RING LANDS OF THE OIL CONTROL AND SECOND COMPRESSION RING.
THE NO. 3 CYLINDER BEARING APPEARED TO HAVE PLASTICIZED DEFORMATION AND WAS OBSERVED PARTIALLY EXTRUDED FROM THE CRANK SHAFT JOURNAL AND CONNECTING ROD, CONSISTENT WITH SEVERE LUBRICATION DEPRAVATION HEAT DISTRESS.
THE NO. 4 CYLINDER BEARING APPEARED TO HAVE PLASTICIZED DEFORMATION AND WAS OBSERVED PARTIALLY EXTRUDED FROM THE CRANK SHAFT JOURNAL AND CONNECTING ROD, CONSISTENT WITH SEVERE LUBRICATION DEPRAVATION HEAT DISTRESS.
INDICATIONS OF MECHANICAL FAILURE DUE TO LUBRICATION DEPRIVATION ARE CONSISTENT WITH A LOSS OF ENGINE RPM. SPECIFIC COMPONENT OR SYSTEM FAILURE IS STILL BEING INVESTIGATED BY NTSB AND THIS REPORT WILL BE AMENDED AFTER THAT DETERMINATION HAS BEEN MADE.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.