Mcdonnell Douglas Corporation

The Boeing Company

Wilfred E Boehringer

Teunes Verhoeven

Michael Allan Long

James V Walker

Alan C Kernik

Terry J Beezhold

Carl Edward Trustee

William V Mutz

Vincent J Pastor

Neal F Gilleran

William V Hutz

Apparatus for providing actuation power to an aircraft flight control surface. The apparatus includes a first actuator and a second actuator, where the second actuator has a bypass mode and an assist mode. The mode of the second actuator is determined by a load on the first actuator. When the second actuator is in the bypass mode, the first actuator provides the actuation power for the aircraft flight control surface. But, when the second actuator is in the assist mode, both the first and second actuators provide the actuation power for the aircraft flight control surface. Accordingly, the apparatus allows the flight control surface to be operated in a more efficient manner with less hydraulic flow being required.

Augmenting flight control surface actuation system and method

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. The attenuator thus produces a pumping of hydraulic fluid to and from the hydraulic actuators of the brake assembly which are timed to damp the torsional oscillating movement of the wheel assembly. The attenuator can be easily retrofitted to virtually all aircraft wheel brake systems without significantly adding to the cost or complexity of such systems.

Brake squeal attenuator apparatus and method

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. After the door has moved away from the exit opening, the cable pulls the frame such that the frame slides along the track and is moved lengthwise with respect to the aircraft away from the exit opening. To close the door, the above operations are reversed. As an aid to opening and closing the door, the door operating system also includes an interlock system that prevents the door from being moved lengthwise along the track until the door has been fully rotated upwardly and inwardly by the torque drum.

Plug door operating mechanism

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.

Wheel and brake assembly

Axial and rotational movement of the torque tube foot of an aircraft's disc brake assembly is restrained to substantially dampen or eliminate the short interval high frequency vibration previously experienced on brake application. Restraining means is employed to restrain the torque tube foot and includes an annular flange member mounted to the axle by an axle sleeve and positioned adjacent a first side of the torque tube foot to stop lateral movement of the torque tube foot in the direction of the first side. Wheel spacer means is also provided containing a cylindrical passage for mounting the wheel spacer means to the axle opposite the annular flange member and on the opposite side of the torque tube foot. The wheel spacer means also contains an annular portion extending radially outwardly from the wheel axis and the annular portion is positioned adjacent the second side of the torque tube foot to stop lateral movement of the torque tube foot in the direction of the second side such that the torque tube foot is restrained from moving in both axial and rotational directions relative to the axle. Vibration damage experienced to brake and landing gear components with brake assemblies of the prior design is avoided.

Restrained aircraft brake apparatus

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. An Electromagnetic Actuator drives the disconnected mechanical system in synchronization with the position of the cockpit controls in the fly-by-wire mode for a given control surface each time the servo actuator(s) for the control surface are electrically commanded by the flight computer. This causes the mechanical system to remain in phase with the position of the control elements as if connected thereto. In the event of a failure of the fly-by-wire system the mechanical system is automatically coupled into the control system through locking actuators which release a coupling mechanism including a interlocking pin, locking cams, clutch or other engagement device and clamps or locks the pilots input to the mechanical control loop thus providing direct mechanical control to the surface actuators with very little transient effects.

Flight control mechanical backup system

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. With this arrangement, the failure modes allowable are latent mechanical failure of the mechanical links in addition to the total failure of any actuator in combination with any inoperative condition in the hydraulic power system. Various arrangements of the basic system are contemplated within the scope of this invention and include the tail end of each actuator's piston rod connected to a swivel beam. This beam is also connected to the control surface with one or more connecting rods. Each actuator is supported by a trunnion, whether directly connected to the cylinder or otherwise and the trunnion must be able to react to full surface hinge moments.

Mechanically redundant actuator assembly

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.

Multi-wheel brake system

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.

Torque linkage damper

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.

Zero leakage valve

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.

Surface hold-down mechanism

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.

Flight control surface coupling system

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.

High lift surface actuation system

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.

Hydraulic power transfer unit

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.

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Fullerton, CA, United States of America

Wilfred E Boehringer