The pilot’s failure to properly manage the airplane’s configuration and airspeed after he shut down the No. 4 engine following its partial loss of power during the initial climb. Contributing to the accident was the pilot/maintenance director’s inadequate maintenance while the airplane was on tour, which resulted in the partial loss of power to the Nos. 3 and 4 engines; the Collings Foundation’s ineffective safety management system (SMS), which failed to identify and mitigate safety risks; and the Federal Aviation Administration’s inadequate oversight of the Collings Foundation’s SMS.