Abstract: A brake squeal attenuator for use with aircraft wheel brake assemblies. The attenuator includes a housing having a piston member and a weight disposed therein. The piston member and weight are biased by a spring disposed within the housing. The housing includes a neck portion which is in fluid communication with the hydraulic actuators of the brake assembly with which the attenuator is being used. The piston thus is biased on one side thereof by the biasing member and on an opposite side thereof by the hydraulic fluid pressure acting thereon. During braking, when torsional oscillations occur in the brake assembly which would otherwise cause objectionable brake squeal to occur, the entire housing of the attenuator, which is fixed to the housing of the wheel brake assembly, moves in accordance with the torsional oscillations which occur. The weight associated with the piston member causes movement of the piston member to lag behind movement of the attenuator housing as the attenuator begins oscillating.

Abstract: The present invention provides a door operating system for opening and closing a door covering an exit opening of an aircraft. More particularly, the present invention provides a door operating system for opening and closing a plug type door typically located on the lower passenger deck of an aircraft. The door operating system includes a frame that is connected to the door of the aircraft and defines a pivot for the door. Connected to the frame is a torque drum and linkage system. The door operating system also includes a motor and a cable drum attached to the opposite end of the track. A cable is connected to the cable drum, the torque drum, and the frame. When opening the door, the motor turns the cable drum, which thereby pulls the cable. The cable rotates the drive torque drum and causes the door to be rotated about the pivot thereby moving the door upwardly and inwardly away from the exit opening.

Abstract: A wheel and brake assembly comprising an axle, a bearing supported on the axle, a wheel rotatably mounted on the axle by the bearing and a torque tube located in a fixed position about the axle. The torque tube includes a torque tube foot extending radially inward from the torque tube to the axle for support by the axle. At least one stator disc is connected with the torque tube and one rotor disc is connected with the wheel for conjoint rotation therewith. An actuator is provided for axially moving the rotor and stator discs into frictional engagement with one another for braking the wheel. A clamp is located at one end of the axle for axially clamping the bearing, torque tube, brake housing and axle. A vibration dampener operatively engages the torque tube and is arranged to attenuate vibrations in the torque tube and inhibit their transmission to the axle.

Abstract: A robust mechanical reversion system which provides the ability to fly and land in the absence of any fly-by-wire controls and which is transparent to the pilot during normal operation. The described invention provides a mechanism which includes redundant linear variable differential transmitters (LVDT) which generates a transmitted signal in proportion to the displacement of the control apparatus in the cockpit. The signal is fed to the flight control computer which determines the magnitude of the change represented by the signal and in turn, commands both the control surface servo actuators as well as an electrical mechanical servo actuator (EMA) located in close proximity to the flight compartment and coupled to the mechanical system to move in proportion to the change.

Abstract: In a mechanically redundant actuator system, the actuator has a structurally redundant members for attaching it between a stationary anchor point to a movable control surface. Specifically the actuator consists of a cylinder body, a double action piston with a piston rod attached to the control surface at one end and a swivel bar at the other end. Single or multiple tie rods are attached between the swivel bar and the movable control surface. Each tie rod can withstand one half the load of the piston rod. Also, trunnion links attach the cylinder body to the structure. Each trunnion links can withstand the full limit load with or without any load factors. The trunnion fittings can be any configuration that provides a structural reaction, and provides a dual load path and freedom of movement in at least two axes. At least two of these actuator units are required per surface. Also, a dual tandem control valve with a hydraulic compensator for each actuator is required.

Abstract: A braking system which employs redundant hydraulic systems. The system has a first hydraulic system coupled to the brake of a first wheel through a first switching valve, and a second hydraulic system coupled to the brake of a second wheel through a second switching valve. Each switching valve will switch the coupled brake to the other hydraulic system, if the pressure within its system falls below a threshold value. For example, if the first hydraulic system fails, the first switching valve switches the first wheel to the second hydraulic system. If the second hydraulic system fails, the second switching valve switches the second wheel to the first hydraulic system.

Abstract: An aircraft landing gear damping mechanism improvement of a damper containing piston means in a chamber of a housing, an orifice in the piston means and Belleville springs disposed in the chamber between the wall of the chamber and the piston means on opposite sides thereof. The improvement comprises means, e.g. in the form of a member having slots therein, and disposed between one end of the Belleville springs and the adjacent chamber wall, providing fluid communication of the inner cavity and outer cavity of the chamber below and above the Belleville springs.

Abstract: A valve having dual seats and dual poppets operating in series to function as either a conventional check valve, or may be operated by an independent piston which may be styled to either combine or eliminate the check valve feature. One seat poppet combination employes a metal-to-metal seal. The other seat poppet combination utilizes a resilient o-ring seal vented so that when the seal is raised from the bottom of its groove, the upstream and downstream sides of the soft seat poppet can communicate. Alternative embodiments provide a family of zero leakage valves for different purposes, e.g. a check valve, pilot operated check valve, and an in line or balanced relief valve with or without the check valve feature by employing generally the same elements with modifications.

Abstract: A mechanical biasing device to drive an aircraft control surface to a predetermined position relative to the main airfoil, either directly or indirectly through a linkage system, while also providing sufficient clamping force at the neutral position so that the airfoil and control surface behave dynamically like a single structure.

Abstract: A flight control surface coupling system which provides a two-element drive coupling between two control surface segments. The first element is a torsion bar that has adequate spring rate to suppress surface flutter yet soft enough to deflect and function as a low load compliance element between sets of drive actuators. The second element is a drive coupling that permits the two surface segments to move freely within its stops. The stops are spaced to allow easy determination of out-of-rig conditions and small enough to provide an effective drive to move one segment through the second segment with a single actuator. Structural fatigue loads are greatly reduced without sacrificing surface positionability.

Abstract: A drive system for high-lift devices on aircraft having two power drive units, one at each end of the connecting torque tube system, so as to force sum the outputs. A one-way brake always insures against inadvertent retraction of the device but allows extension. An asymmetrical protective device prevents the high-lift device from an asymmetrical condition even after a combined power loss and mechanical failure of the torque tube. The power drive units consist of hydraulic motors driving through a gear box and a no-back brake combination and are controlled by a servo valve.

Abstract: A vane for use in switching a hydraulic port formed in a cylindrical surface, the vane having a wiper at the top of the vane body with a ring shaped surface whose inner edge is shaped to match the shape of the hydraulic port and surface shaped with a contour which is a portion of a cylinder so that it can mate for sliding contact with the interior cylindrical surface about the port. A ring shaped undersurface adapted to have pressure applied thereto is provided underneath the ring shaped surface to provide the force by which the vane is held against the cylindrical surface while port pressure is provided underneath the vane on an area to balance with the port area.

Abstract: A hydraulic system having two pumps, typically driven by two independent prime movers, a primary and secondary reservoir and associated valving to permit the system to run as one system or two independent systems, all for the purpose of redundancy and safety. The system senses fluid level in the primary reservoir and actuates the valves to establish two independent hydraulic systems, each with its own reservoir, when the fluid level drops below a predetermined level. The system is particularly advantageous in twin-engine aircraft where three hydraulic systems are employed, one off of each engine, and the third system uses two pumps, one driven by each engine.

Abstract: A mechanical flowmeter is provided for measuring the flow of hydraulic fluid in a system in which the flowmeter is connected. The flowmeter contains a spring biased piston which is responsive to the rate of flow through an annular space surrounding the piston as it moves in a tapered bore. A toroidal armature of ferrous (magnetic) material is mounted on a rod extending from the piston for movement therewith. Movement of the armature and the piston rod within a hollow guide is tracked by a permanent magnet of toroidal shape which is mounted surrounding the guide in sliding relationship. A sight glass surrounding the guide and magnet is calibrated with a scale for converting the position of the magnet to an indication of flow rate. For fluid flow in the reverse direction, the piston is moved out of the tapered bore, thus permitting free flow in the reverse direction with minimal energy loss.

Abstract: A fluid actuator where an outside cylinder envelopes an inside cylinder producing four chambers, two for the power stroke and two for synchronization, for application where two or more cylinders are to drive a single load such that all cylinders advance at the same rate by cross plumbing synchronizing chambers. The combination is provided with valve means which opens at the end of each stroke to realign the actuators.

Abstract: A manual/automatic brake valve of the OR configuration wherein either the servo command or the manual pedal force, whichever is the greatest, overpowers the other and is the exclusive controller of the brake pressure and springs are provided to generate a feel force during manual actuation. The feel force is independent of valve spool displacement as a result of the automatic servo input and as a result the feel force is relative to manual brake position and ignores brake force as a result of the servo command.

Abstract: A seal for use in a cylindrical groove in a cylindrical item positioned in a cylinder such as a rotary valve where the seal is subjected to reciprocating forces as the item and the cylinder rotate with respect to each other. The seal has two adjacent pairs of outer sealing rings with each pair being backed up by a pair of backup rings which are positioned to bear outwardly on the sealing rings. A spring is positioned to push the pairs of sealing rings and the associated backup rings to the opposite sides of the groove to form the side seals and hydraulic pressure is provided underneath the rings to urge them outwardly to form the outward seal.

Abstract: A hydraulic actuator cylinder primarily for the actuation of aircraft landing gear in which the rod end is made integral with the piston rod with the attaching threads positioned inside the cylinder. The piston head is designed to float on the piston rod plus or minus the amount of adverse tolerance conditions that are possible in the landing gear installation.

Abstract: A multi-piston motor pump for the transfer of hydraulic energy from one hydraulic system to another without the transfer of fluid therebetween. A plurality of pistons are maintained in predetermined phase by a nutator mechanism or spider which is then used to rotate a shaft connected to valving means for the pistons which controls fluid to, or away from the pistons in a predetermined manner. The motor pump unit, in large measure, is made possible by improved couplings between the spider and the pistons that provide complete motion freedom, yet maintain definite position between the pistons and the spider. In addition, a rotary valve arrangement is disclosed which reduces the start-up friction loads of the unit to a minimum while being relatively reliable and easy to mechanize.

Abstract: A check valve having dual seats and dual poppets which act in a series arrangement as a double valve. One seat poppet combination employs an o-ring type seal and the second seat poppet arrangement employs a metal-to-metal sealing surface. Each seat poppet arrangement performs in typical check valve fashion. The mechanics of operation of the dual valve series arrangement is such that the soft seal valve always opens and closes under essentially zero flow conditions preventing extrusion or errosion of the soft seal and preserving the zero leakage sealing surface.