Abstract: A pressure relief device for preventing over pressurization of a propeller hub is disclosed. The pressure relief devices is designed to fit within a ball hole opening in the hub arm of the hub. The pressure relief device includes a housing which sealably interfaces with an inner wall of the ball hole opening and a pressure relief insert which sealably interfaces with the housing. The pressure relief device includes a plurality of fracture tabs which engage an end of the housing exposed to hub cavity pressure. The fracture tabs are designed to break at a design pressure allowing the pressure relief insert to be forced out of the housing thus breaking the seal between the pressure relief insert and housing thereby venting the hub cavity.

Abstract: A system for controlling propeller blade pitch is disclosed. The system comprises a transfer tube, wherein the transfer tube defines an element of the rotatable portion and wherein the transfer tube is non-translating relative the rotatable and non-rotatable portions. A transfer bearing for providing hydraulic fluid to and interfacing with the transfer tube is also used, wherein the transfer bearing is located on the non-rotatable portion. The system further includes a pitch change actuator and a mechanism form for actuating the pitch change actuator, wherein the mechanism is fluidically connected to and translatable relative to the transfer tube. A device for measuring blade angle of the propeller blade is also provided, wherein the device is separate and distinct from the transfer tube.

Abstract: An improved electronic hydraulic propeller control designed as a retro-fit kit for existing Hamilton Standard Division 54460 and 54H60 propeller controllers includes an apparatus for controlling the pitch angle of a propeller blade. The retro-fit kit includes an electro-hydraulic servo valve, an electronic controller, a protection valve, and a propeller maintenance interface panel. These components functionally replace the existing hydromechanical propeller control system without reconfiguration of the existing interface. The apparatus converts mechanical inputs of the propeller and airframe systems to electronic signals, which can be measured by the electronic control. The apparatus also receives and converts the electronic control's commands into hydraulic pressure and flow changes through an electro-hydraulic servo valve. The electronic controller performs the required calculations to interpret and then react to changes in the propeller/airframe systems.

Abstract: The hydraulic propeller system of the present invention has a central hub including a stationary portion and a rotatable portion. A plurality of propeller blades are connected with the rotatable portion, wherein each of the plurality of propeller blades has an adjustable pitch and a counterweight biasing the blades in a first pitch direction. An actuating mechanism is used for adjusting the pitch of each of the plurality of propeller blades. And a valve for locking the propeller blades at a last commanded pitch is further provided. At least the valve and the actuating mechanism are located on and rotatable with the rotatable portion.

Abstract: Pitch change for a variable pitch propeller or fan of the type utilized in a gas turbine engine is effectuated by the unique application of a bidirectional electrical induction AC motor and an electrical DC induction brake operatively connected to the pitch change actuator. The motor can be utilized in a slip speed range encompassing from a positive slip speed to zero slip speed and negative slip speeds which removes the limitations on the gear ratio.

Abstract: The pitch change mechanism for a variable pitch propeller blade or Advanced Ducted Propulsor (ADP) interconnecting the pitch change actuator and the propeller blades of the type that includes a trunnion attached to the root of the propeller blade, the connecting mechanism includes in one embodiment a translating ball screw nut interconnecting the trunnion through a yoke and a cooperating sliding pin and arm connector. In another embodiment where a hydraulic piston is included in the pitch change actuator the cylindrical housing supports a plurality of circumferentially spaced pins that are in sliding relationship with a rod attached to the trunnion. The trunnions in both embodiments are extended to make the interconnections. Means are provided to prevent the blades from binding up during pitch change movements. This invention eliminates the heretofore utilized sliding anti-rotation spline and the multiple linkage connectors.

Abstract: The pitch of either a fan or propeller driven by a gas turbine engine is changed by utilizing a pair of impulse turbines interfacing between the stationary and rotating portion of the fan or propeller and utilizing a servo control responding to a desired pitch input signal for actuating the normally inactive impulse turbines during fixed pitch to drive the impulse turbine which in turn is operatively connected through a pitch change actuator to change the pitch in accordance with the input signal.

Abstract: A pitch change system (30) for varying the pitch of the blades (16) of a multi-bladed propulsor (10) comprises a pitch change actuation assembly (40) and a pitch change drive assembly (70) for selectively actuating the pitch change actuation assembly (70) whenever it is desired to change blade pitch. The pitch change actuation assembly (40) comprises a ballscrew (42), a ballscrew nut (44) threadably mounted to the ballscrew (42), and a pitch stop assembly (100) having a retractable feather stop (135) which in its normal position prevents the ballscrew (42) from driving the ballscrew nut (44) to move the blades (16) beyond the coarse pitch setting corresponding to blade feather, but in its retracted position permits the ballscrew (42) to drive the ballscrew nut (44) to move the blades (16) through feather to a desired reverse pitch setting.

Abstract: A pitch change actuation system for changing the pitch of the blades (16) of a prop-fan propulsor (10) comprises a translating pitch change actuator (30) and a flexible feather latch member (50) including a feather stop (56) and a feather latch (58), the feather latch member (50) being selectively releasable so as to permit the pitch change actuator (30) to drive the blades (16) through feather to a desired reverse pitch setting. Pitchlock lugs (96) and (98) operatively engage a pitchlock screw lug (97) on a pitchlock screw (80) to provide pitchlock screw stops at full reverse pitch and feather, respectively, with the pitchlock lug (98) being selectively displaceable so as to permit the pitchlock screw (80) to rotate when the pitch change actuator (30) is translated to drive the blades (16) through feather to reverse pitch.

Abstract: A pitch control system has a main electronic control, a mechanical back-up control and a switching system for transferring pitch control from the electronic to the mechanical control in the event of electronic control failure. The switching system utilizes a switch for comparing the output of the electronic and mechanical control systems, the switch choosing the mechanical system if a failure occurs in the electronic control system. By utilizing the switching system, a failure of the electronic control does not permit the blades to go to feather. In certain failure modes, an enable valve or an enable solenoid locks out the switch, to ensure mechanical pitch change control.

Abstract: A propeller system has a pair of hub assemblies driven in counter-rotation, each hub assembly having a mechanical pitch change actuator, each actuator being provided with a pitch lock that rotates simultaneously with the motion of the actuator to allow the actuator to set propeller blade pitch, but locks the propeller blade positionally when not rotating simultaneously with the actuator, and a differential for transmitting a pitch change signal across a rotating gap between the two hub assemblies and for providing power to a means for providing the pitch change signals. A pair of motors provide the rotative signal to set the pitch of the blades in each hub assembly. One of the pair of motors drives the actuator towards high pitch and the other motor drives the actuator towards low pitch. A synchronizer coordinates the signals of the first and second motors so that a pitch lock moves simultaneously with the actuator.

Abstract: Hydraulic fluid is input to a transfer tube of a variable pitch propeller system forward of a rotatable portion of a controller. A transfer bearing is provided about the drive shaft to transfer hydraulic fluid therethrough and between the drive shaft and the transfer tube to transfer hydraulic fluid from the drive shaft into the transfer tube, such transfer bearing allowing relative rotation between the housing and the drive shaft and between the drive shaft and the transfer tube. The transfer tube is slideably connected to the rotatable portion of the controller.

Abstract: An oil dam consists of a pair of parallel plates, each plate having a hole passing therethrough, each hole being disposed at a radial position within each respective plate such that the oil may flow through the holes when the dam is rotating. The hole in one plate is offset circumferentially from the hole in the other plate so that both of the holes are not below a surface of the oil flow when the dam is in a stationary position.