The pilot/owner was landing the experimental, amateur-built airplane at the conclusion of a night cross-country flight. The pilot described that he flared the airplane slightly high and that it, “skipped and then settled.” The landing roll seemed normal until the left main landing gear collapsed and the airplane departed the runway. The pilot further characterized that the touchdown wasn’t particularly hard, compared to landings he had previously made in other airplanes. The airplane’s horizontal stabilizer and elevator were substantially damaged during the runway excursion. Following the accident, the pilot had the airplane repaired by its original builder, which included replacing a section of threaded rod on the left main landing gear that had broken, which was part of the landing gear down-locking mechanism. Based on this information, it is likely that the failure of the threaded rod resulted in the landing gear collapse and subsequent runway excursion.