At about 1030 Eastern time, the experimental, amateur-built airplane was substantially damaged when it impacted terrain during a forced landing following a partial loss of engine power. The commercial pilot in the front seat and the airline transport pilot in the rear were seriously injured. Visual conditions prevailed. About five minutes after departing and while cruising at about 3000 feet msl, the airplane’s engine lost power, but continued to run with very low output. The front-seat pilot attempted remedial actions, to no avail. The rear-seat pilot then took control of the airplane and turned towards a nearby airport. Shortly before reaching the divert runway, the rear-seat pilot heard a loud “bang”: