Propeller module for an aero gas turbine engine

A propeller module for a gas turbine engine comprising a first multi-bladed propeller, a second multi-bladed propeller, a shaft and a reduction gear train,

• the first and second multi-bladed propellers being coaxial and driven in contra-rotation by the shaft via the reduction gear train,
• the reduction gear train being positioned axially between the first and second multi-bladed propellers, the reduction gear train comprising a sun gear, a plurality of planet gears and an annulus gear, the sun gear being driven by the shaft, the planet gears being driven by the sun gear and the annulus gear being driven by the planet gears, the planet gears being rotatably mounted in and driving the carrier member, the annulus gear and the carrier member being driven in contra-rotation by the planet gears,
• a first pitch change means to change the pitch of the blades of the first multi-bladed propeller, a second pitch change means to change the pitch of the blades of the second multi-bladed propeller and a pitch change power unit, the pitch change power unit being mounted on the second multi-bladed propeller to operate the first and second pitch change means,
• the first pitch change means comprising first drive means, first pitch change gears and compensating gears,
• the first drive means being rotatably mounted on the first multi-bladed propeller and being adapted to rotate the blades of the first multi-bladed propeller,
• the first pitch change gears comprising first gears, second gears and spindles, the spindles extending axially through the carrier member, the first gears and second gears being secured to opposite ends of the spindles, the spindles being rotatably mounted on the carrier member, the first gears of the pitch change gears being arranged to drive the first drive means, the compensating gears being rotatably mounted on the carrier member and being arranged to drive the second gears of the first pitch change gears so that a fixed blade pitch of the first drive rotates in the same direction and at the same speed as the first multi-bladed propeller,
• the pitch change power unit being adapted to drive the compensating gears so that relative rotation occurs between the first drive means and the first multi-bladed propeller to change the pitch of the blades of the first multi-bladed propeller,
• the compensating gears allowing the pitch of the blades of the first multi-bladed propeller to be set independently of the differential speed between the first and second multi-bladed propellers.