Accident Overview
On October 3, 2020, at approximately 1600 eastern daylight time, an experimental, amateur-built Quad City Challenger II, registration N129AY, was substantially damaged during a forced landing near Northfield, New Hampshire. The private pilot was not injured. The aircraft was operating under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Sequence of Events
The pilot reported that he performed a full-stop landing at Laconia Municipal Airport (LCI) in Laconia, New Hampshire, then departed direct to Hawthorne-Feather Airpark (8B1) in Hillsboro, New Hampshire, maintaining an altitude of 2,000 ft. About 10 to 15 minutes into the flight, the engine suddenly stopped. The pilot executed a forced landing in a hay field.
After landing, the pilot verified adequate fuel level, checked for fuel leaks, and inspected the fuel filter and lines for contamination or air bubbles, finding no anomalies. He then examined the ignition system, confirming all spark plugs and wires were secure and visible wiring from the engine to bulkhead connectors was unchanged. The pilot rotated the propeller by hand to check for engine seizure due to oil starvation; the propeller spun normally without resistance. The exhaust system was properly connected, and no engine anomalies were noted.
The pilot reboarded the aircraft, performed the startup procedure, verified the auxiliary electric fuel pump was operating audibly, and the engine started immediately. A magneto check confirmed both magnetos functioned properly. The engine ran for about 5 minutes as he monitored temperature and voltage within normal ranges. He taxied to a higher point in the field near a house, shutdown and restarted the engine, rechecking all systems before departing. After a run-up, he performed a short-field takeoff. While climbing through about 100 ft, the engine abruptly shut off again. He completed another forced landing into the same field, during which the fuselage sustained damage.
Engine Examination
Post-accident examination revealed that the No. 1 piston, rings, and cylinder walls were scored and discolored, indicating a lack of lubrication within the No. 1 cylinder. The engine manufacturer's analysis determined that the engine experienced a piston seizure. Inspection of the oil injection system found that an oil injection line supplying oil to the No. 1 cylinder was pinched by the starter motor mounting flange. The pilot recalled performing maintenance in that area about two weeks prior and considered that he may have inadvertently caused the pinched line.
Conclusion
The accident was attributed to a piston seizure resulting from inadequate lubrication caused by a pinched oil injection line.