Mcdonnell Douglas Corporation

Teunes Verhoeven

Wilfred E Boehringer

James W Downing

Terry J Beezhold

William V Mutz

William V Hutz

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 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

In an aircraft control system a standby cable system which does not significantly affect existing control system friction, but detects when the primary cables are severed and actuates an alternative elevator control mechanism. The standby cable loop of the instant invention consists of two similar type mechanisms located outside the uncontained rotor or propeller shrapnel area. One mechanism attaches to the primary cables and is located forward of the engine and the other is located aft. Each mechanism operates such that negligible friction is added because during normal control motions the standby cable loop does not move, only individual elements input cranks are in motion. The primary cables are provided with an index cable that is routed close to and parallel to the primary cables. In the event the engine shrapnel cuts the primary cables, the index cable will also be cut because of its close proximity to the primary cables and due to the fact it is of smaller size. When the index cable has severed, a spring loaded crank through linkage causes an alternate push-pull cable to be engaged.

Standby control 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 mechanical power transmission apparatus, of the differential gear type, for actuating an airplane control surface requiring two independent actuator inputs to a single control surface. Asymmetric loading to the control surface is accommodated by a mechanical fuse link. The fuse link is provided by employing a shear pin to attach the pinion gear to the pinion shaft, designed to fail at a predetermined differential torque between the two driven bevel gears. Positive disengagement of the gears is provided following fuse link release.

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Long Beach, CA, United States of America

Teunes Verhoeven