A mounting system for a planetary gear train (30) in a gas turbine engine (10) comprises a support strut (56), a deflection flange (74) and a deflection limiter (52). The support strut extends between a stationary engine case (42) and a rotating engine shaft (22) that provides input to the planetary gear train in the gas turbine engine. The deflection flange extends from a rotating output component (68) of the planetary gear train. The deflection limiter is connected to the support strut and engages the deflection flange when the gear train becomes radially displaced.