Abstract: A system for changing pitch in aircraft propfans is disclosed, in which a motor, located at a stationary position, changes pitch of the blades by of a gear train. Three features of the system are that a feather brake can override the motor and drive the blades toward feather; a unison brake can prevent pitch from undergoing excursions toward fine pitch when propeller speed exceeds a limit; and the motor is non-rotating in the absence of pitch change. A pair of such systems can be used in a counterrotating propfan system, in order to independently change pitch of the propfans.

Abstract: In one type of aircraft propulsion system, propeller blades are mounted on a ring which surrounds a turbine. An annular space exists between the turbine and the ring. If a propeller blade should break free, the unbalanced centrifugal load tends to deform the ring. The invention reduces the deformation, as by locating spacers between the turbine and the ring.

Abstract: The invention concerns aircraft propellers of the variable pitch type. Each propeller blade is carried by a trunnion which is rotatably mounted to a common ring. Each trunnion contains a reduction gear set which is driven by a radial shaft. The reduction gear sets multiply the torque applied by the shafts, thus allowing shafts of reduced diameter to be used. The reduced diameter is important when the shafts must pass through a turbine flowpath, and thus be concealed within turbine blades. The reduced diameter shafts can be easily concealed within turbine blades without redesigning and compromising blade aerodynamics.

Abstract: The invention relates to pitch-change systems in aircraft propellers. The invention includes redundant planetary gear systems, each of which can independently change pitch if the other fails. The invention also includes a system for reducing displacement of the planets, which can occur during a failure.