Amateur-built LONG EZ accident near Medicine Bow, Wyoming, September 5, 2022

The NTSB's narrative final · quoted from the NTSB record

According to the pilot, he and a passenger were on a cross-country flight when, at approximately 7,500 feet above mean sea level (msl), the aircraft began aggressively shaking. The pilot initially flew toward a nearby airport but decided to land on a highway. The airplane landed hard, veered off the road, and impacted terrain. Subsequently, the airplane nosed over onto a fence and sustained substantial damage to the fuselage and wings. During the postaccident examination of the engine, excessive oil and carbon were discovered on the No. 4 cylinder valve springs, guide, stem, and retainers, which is consistent with exhaust blow-by. In addition, approximately 0.8 inches of the No. 4 exhaust valve stem and valve head were not recovered from the cylinder and engine. The remaining valve stem had excessive play within the valve guide. The fracture of the stem portion of the exhaust valve was the result of a fatigue crack that emanated from severe corrosion pits at the outer surface of the stem, which resulted in a loss of engine power. The engine's logbook entries revealed that it was last overhauled 41 years before the accident, exceeding Lycoming's recommendation of 12 years. It is likely that the No. 4 exhaust valve deteriorated from age and likely fractured from a fatigue crack.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.