On May 21, 2022, about 1353 eastern daylight time, an Evektor-Aerotechnik Sportstar Plus, N503RK, was substantially damaged when it was involved in an accident near Carroll, Ohio. The private pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that his airplane had been sitting for a few months for maintenance. He stated that after a thorough external inspection, he started the engine and let it run to ensure there were no anomalies. After all engine checks were completed, he taxied to the run-up area and prepared for takeoff. After takeoff, the pilot noticed that the engine was not developing full power. He leveled off to regain airspeed and reported the engine gained about 200 rpm. Ge turned north toward the practice area, but the engine once again started to lose power. He then turned back toward the traffic pattern for the runway. While on the downwind leg, the engine “quit,” and the pilot radioed “MAYDAY.” He made a forced landing in a field adjacent to the airport. During the landing flare, the airplane landed hard and the right main and nose landing gear collapsed. Postaccident inspection of the airplane by a Federal Aviation Administration inspector revealed the right horizontal stabilizer and fuselage were buckled. An examination of the engine revealed that when Nos. 1 through 3 cylinder heads were removed the pushrod O-rings were found installed incorrectly. The O-rings were crushed, partially disintegrated, and O-ring material was found in the bore of the crankcase. The No. 4 cylinder head was removed, and the intake pushrod tube O-ring was extruding from the bore. No breaches were found in the oil or cooling system. The crankshaft would not rotate by hand. The cylinder heads were subsequently removed. The No. 4 connecting rod was separated from the crankshaft. The No. 3 piston displayed scoring and liberated pieces of the pushrod O-rings were obstructing oil ports that fed the No. 4 connecting rod bearing. A review of the maintenance logbooks for the airplane did not reveal any recent engine maintenance that would require the removal of the cylinder heads. It was noted in the maintenance logbooks that the cylinders were removed and reinstalled for repair on August 4, 2013, at a tachometer time of 480 hours. This was 8 years and 10 months and 58.8 tachometer hours prior to the accident.