On July 7, BC Ferries concluded that a missing cotter pin was to blame. The pin normally retained a nut on a linkage between an engine speed governor and the fuel control for one of the engines. Without the pin, the nut fell off and the linkage separated, causing the engine, clutches, and propellers to increase in speed until overspeed safety devices activated and shut down the entire propulsion system. The faulty speed governor had been serviced 17 days before the incident during a $35-million upgrade, and the cotter pin had not been properly replaced at that time.