 After rebuilding with a larger propeller engine output was reduced from to making them suitable for a trainer, and these were fitted to both M.F.8 and M.F.10 trainers.By early summer 1936 all M.F.8s had been rebuilt with Armstrong Siddeley Cheetah IIA engines however with the engine out of production spare parts once more became a problem.The Walter Regulus engine had performed well during the testing in Horten and examples were purchased, however the engine did not perform as well as anticipated and in 1938 the Czech factory ceased production.