 At this point pilot confidence in the aircraft reached an all-time low, with seven officer pilots writing a letter of protest to the Ministry of Defence, voicing their opposition to the further use of the M.F.9.The criticism led to the halting of work on five M.F.9s then under construction (F.136, F.138, F.140 and replacement machines F.130 and F.132), although one almost complete M.F.9c (F.142) was finished in February 1932.F.142 and the incomplete aircraft had steel tube hulls instead of the wooden constructions of the earlier aircraft.