 As the weak Hispano-Suiza engine prevented the M.F.9 from being a truly effective fighter aircraft work was carried out from the autumn of 1929 to the spring of 1931 to find a different engine to have in reserve and install in case of war.Two engines were tested, first a Bristol Jupiter which at the time was the standard engine of the Norwegian Army Air Service's Fokker C.V-E scout-bombers, and secondly an Armstrong Siddeley Jaguar VII 14-cylinder air-cooled engine.However, accidents involving the aircraft entering uncontrolled spins continued with another aircraft being lost on 25 July 1930.