Accident Overview
On April 13, 2019, at about 1145 Pacific daylight time, an experimental, amateur-built Europa XS, registration N120EJ, was substantially damaged during a forced landing in a plowed field near Winters, California. The airline transport pilot, who was the sole occupant, sustained serious injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a personal flight.
Pilot Actions
The pilot reported that he had not flown the airplane for six months prior to the accident. Two days before departure, he sprayed oil into each cylinder through the spark plug port holes, then manually rotated the engine about 30 times without observing any binding. After cleaning and reinstalling the spark plugs, he attempted to start the engine but found the battery weak. After charging the battery, the engine started normally two days later. The pilot departed uneventfully, flew north, then turned west and climbed to 3,000 ft. While turning south and advancing power to 2,950 rpm, he heard a loud noise accompanied by a sudden vibration, followed by a partial loss of power. He turned toward the departure airport and reduced engine power, noting a low exhaust gas temperature on the multifunction display (MFD) and concluding that the No. 5 cylinder had failed. Upon advancing the throttle again, the engine continued running with vibration but eventually lost all power as he approached the airport. During the forced landing to a plowed field, the nose landing gear dug into the dirt, causing the airplane to nose over and come to rest inverted.
Maintenance History
According to Federal Aviation Administration records, the airplane was registered to the pilot on November 15, 2011. It was powered by a Jabiru 3300 120-horsepower air-cooled, reciprocating engine. The most recent condition inspection was completed on May 11, 2018, at a total time of 185 flight hours. Subsequent maintenance work performed in June 2018, though not documented in the logbook, involved removal and reinstallation of pistons for cylinders 3 and 5 to install new piston rings. The pilot stated that the airplane had accumulated about 4 flight hours since the last condition inspection.
Postaccident Examination
Photographs provided by law enforcement revealed substantial damage to the right wing and empennage. Postaccident examination of the engine showed that the rocker box covers were mostly normal, except for the No. 5 exhaust valve rocker arm which moved freely. The cylinder No. 5 piston head exhibited multiple gouges, striations, galling, and polishing consistent with visible cylinder wall damage. The journal housing the wrist pin on the backside of the piston had separated and was found inside the engine case. Both wrist pin circlips were recovered: one intact from the oil sump and the other broken into two pieces within the engine case. The intact circlip showed no visible imperfections and was installed uneventfully in another piston.
The Jabiru 3300 engine overhaul manual includes instructions for installing snap rings (circlips) in the wrist pin journals, specifying that the rounded side should face the retained item and that overcompressing or improperly installing the clip can lead to failure. The manual warns that loose clips can wear the piston groove, potentially freeing the wrist pin and causing engine failure. The pilot did not recall his installation method but stated he may have installed the circlips incorrectly.