SYSTEM AND METHOD FOR LANDING GEAR RETRACTION

Abstract

A retractable landing gear on an aircraft is operated by a landing gear control system 20 having a manually operable lever 26 movable from a first, e.g. gear-down, position to a second, e.g. gear-up position, in response to which a signal (e.g. a gear-up command) is outputted causing the landing gear to move to an up position. The landing gear control system 20 also includes a motor 40 configured to move the lever 26 in dependence on a signal, for example a signal received by a landing gear lever control unit 42 from a take-off detection system 46 which indicates that the aircraft has taken-off. Thus, the lever 26 may be considered as being configured both to be operated by a pilot of the aircraft manually and to be operated by the motor automatically.

Claims

1. A landing gear control system for an aircraft having a retractable landing gear, the landing gear control system comprising a lever assembly comprising a manually operable lever movable from a first position to a second position, the lever assembly arranged, in response to the lever moving to the second position, to output a gear-up command that causes the landing gear to move from a down position to an up position, and a motor configured to move the manually operable lever from the first position to the second position in dependence on a signal received in response to the aircraft taking-off, the manually operable lever configured to be operated by a pilot of the aircraft manually and operated by the motor.

2. The landing gear control system according to claim 1, wherein the lever assembly and the motor are arranged to allow a pilot to override, by manual operation of the lever, movement of the lever by the motor.

3. The landing gear control system according to claim 2, wherein the lever assembly comprises one or more sensors configured to detect manual operation of the lever at least during movement of the lever by the motor.

4. The landing gear control system according to claim 1, wherein the motor is arranged to provide force feedback to a user when operating the lever.

5. The landing gear control system according to claim 1, further including a control module arranged to detect when the aircraft has taken off and, in response to the detection of the aircraft having taken off, to output a signal which causes the motor to move the lever from the first position to the second position.

6. The landing gear control system according to claim 1, including a computer processing module arranged to receive the gear-up command from the lever assembly and to control the movement of the landing gear to the up position.

7. An aircraft including a retractable landing gear, a landing gear retraction control system, and a landing gear lever configured to move to a gear-up position which movement causes a control signal to be sent and received by the landing gear retraction control system to perform retraction of the landing gear, wherein the lever is configured to: (a) move automatically to the gear-up position in response to a take-off signal, and (b) allow for manual override by the action of a pilot of the aircraft of the automatic movement.

8. An aircraft including a landing gear control system according to claim 1.

9. A method of retracting a landing gear on an aircraft after take-off comprising: automatically moving a landing gear lever after take-off towards a gear-up command position; issuing a first command to retract the landing gear in response to the landing gear lever being automatically moved to the gear-up command position; retracting the landing gear in response to the command; before at least one of (a) the landing gear fully retracting in response to the command and (b) the landing gear lever reaching the gear-up command position, a pilot of the aircraft moves the landing gear lever away from the gear-up command position and thereby stop the retraction of the landing gear, the pilot subsequently manually moves the landing gear lever to the gear-up command position; issuing a second command to retract the landing gear in response to the pilot subsequently manually moving the landing gear lever to the gear-up command position, and in response to the second command, retracting the landing gear.

10. The method according to claim 9, wherein the pilot initiates the manual moving of the landing gear lever away from the gear-up command position during automated movement of the landing gear lever to the gear-up command position, and in so doing causes the automated movement to be modified.

11. The method according to claim 9, wherein, for at least some of the manual operation of the lever by a pilot, the pilot receives force feedback from processor-controlled driving of the lever.

12. A method of retracting a landing gear on an aircraft after take-off, the aircraft comprising a landing gear lever arranged to be automatically moved after take-off towards a gear-up command position at which a command would be issued which would cause the landing gear to be retracted, the method comprising before the landing gear lever is automatically moved to the gear-up command position, the pilot manually moving the landing gear lever to the gear-up command position so that a command is then issued to retract the landing gear, and in response to the command so issued, the aircraft then retracting the landing gear.

Description

DESCRIPTION OF THE DRAWINGS

[0024] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

[0025] FIGS. 1 and 2 show an aircraft with its nose landing gear and main landing gear assemblies in a retracted position.

[0026] FIGS. 3 and 4 show the same aircraft with its nose landing gear and main landing gear assemblies in an extended position.

[0027] FIG. 5 shows a landing gear control system according to a first embodiment.

[0028] FIG. 6 shows a sequence of steps used to retract a landing gear in accordance with the first embodiment.

[0029] FIG. 7 shows a landing gear control system according to a second embodiment.

[0030] FIG. 8 shows a landing gear control system according to a third embodiment.

DETAILED DESCRIPTION

[0031] Embodiments of the present invention relate to the retraction of a landing gear on an aircraft shortly after take-off. Such an aircraft is shown in FIGS. 1 to 4. FIGS. 1 and 2 show the aircraft 10 with its nose landing gear (NLG) and main landing gear (MLG) in the retracted position (i.e. stowed). FIGS. 3 and 4 show the same aircraft 10 with its NLG 12 and MLG 14 in the extended position (i.e. deployed).

[0032] FIG. 5 shows a control system 20 for retracting (and also extending) a landing gear 14 according to a first embodiment. The control system comprises a Computer Processing Module (CPM) 22, a landing gear lever (LG lever) assembly 24 and various other controllers 42, 46. There may be two such CPMs, which operate, as two independent sides of an avionics control system, thus providing redundancy. Only one side of the system will be described herein. The CPM 22 is configured to perform, on receipt of an appropriate UP signal, a sequence of steps for retracting the landing gear and also, on receipt of an appropriate DOWN signal, a sequence of steps for extending the landing gear. The pilot is able to cause such an UP (or DOWN) signal to be sent by means of operating a lever 26, provided for that purpose in the flight deck of the aircraft. In FIG. 5, the lever 26 is shown in the UP position.

[0033] The landing gear bay is associated with doors 28, which are operable to close over the aperture through which the landing gear 14 extends (substantially closing over the aperture when the landing gear is retracted and partially closing over the aperture when the landing gear is extended). Locks are provided for locking the doors in the closed position. Various valves (collectively schematically represented by the box labelled with reference number 30) and associated solenoids (collectively schematically represented by the box labelled with reference number 32) are provided for the operation of the locks. The CPM 22 is configured to issue control signals, which cause movement, activation (for example energizing of a solenoid), deactivation, or other operation of a physical part of the landing gear extension/retraction apparatus. Such control signals may be converted/modified (for example, digitally processed and/or converted between a digital signal and an analogue signal) by avionics systems between transmission from the CPM and receipt by the intended recipient part (solenoid, for example). Also provided are sensors (represented by boxes 34) for detecting when the doors are open/closed and when the locks are locked/unlocked. The CPM 22 is thus also configured to receive sensor signals from such sensors. Such sensor signals may be converted/modified (for example, digitally processed and/or converted between an analogue signal and a digital signal) by avionics systems between transmission from the sensor and receipt by the CPM.

[0034] FIG. 6 shows a sequence of steps that are performed when retracting the landing gear, in accordance with the first embodiment. As a first step 310, the LG control lever moves to the UP position. Then, as a second step 330, the door uplocks are released. As a third step 340, the LG bay doors are opened. Then as a fourth step 350, the LG is retracted. As a fifth step 360, the doors are then closed. Then as a sixth step 370, the door uplock is confirmed.

[0035] In accordance with the first embodiment, the LG lever 26 is both manually movable by the pilot and automatically moveable by a motor 40. The motor 40 receives a control signal from a landing gear lever control unit, LGLCU, 42. The LGLCU 42 receives outputs from various sensors associated with the lever and with the motor (only two such sensors 44 being shown in FIG. 5 for the sake of simplicity) to enable the LGLCU to provide force feedback to the pilot when operating the lever. The LGLCU 42 receives a signal from a take-off detection system (TODS) 46. The TODS 46 uses a variety of measures, including all of pitch angle, rate of ascent, altitude and a weight on wheels measure, to determine with certainty that the aircraft has taken off. When the LGLCU 42 receives a signal from the TODS 46 confirming take-off, the LGLCU 42 sends a signal to the motor 40 to move the lever 26 from the DOWN position to the UP position. Once the lever has been fully moved to the UP position, the LG lever assembly 24 outputs a signal which is sent to the CPM 22 to start the sequence of steps that causes the LG 14 to be retracted.

[0036] Thus, in a typical operation sequence, the aircraft takes off, the LGLCU causes the lever to move automatically from the DOWN to the UP position, and once the LG lever has reached the UP position, the CPM automatically starts the retraction of the LG 14. The pilot is however able to intervene and/or override the movement of the LG lever at any time, by manual operation of the lever. The sensors 44, motor 40 and LGLCU 42, all cooperate together to detect and react to manual operation of the lever. One such case might be when the LG lever starts to move automatically after take-off and the pilot takes a decision to prevent the landing gear from being retracted automaticallyand thus intervenes. In such a case, the LGLCU allows the pilot to move the LG lever back to the DOWN position and prevents automatic movement of the LG lever to the UP position (until the system resets by means of the pilot having manually moved the LG lever to the UP position). Another scenario in which a pilot might need to intervene is if the LG lever is not automatically moved after take-off soon enough, in the pilot's opinion. In such a case, he or she might intervene to move the LG lever manually before the motor starts to move it. The pilot may additionally (or alternatively) move the LG lever manually at a faster speed (of rotation) to the UP position than would be caused by operation of the motor alone. The first embodiment lends itself well to being retrofitted onto an existing aircraft and/or being featured in a new aircraft assembly with little modification to existing systems on the aircraft. All that is required is the integration of a force feedback motor system on the LG lever, a suitable control processor (the LGLCU) and the provision of a signal feed to the LGLCU confirming take-off from one or more existing aircraft systems. All other components may already be part of the existing aircraft.

[0037] FIG. 7 shows a second embodiment, using the same reference numerals. Only the significant differences will now be described. The reference numerals/boxes for the LG doors, the valves, associated solenoids, and sensors are omitted (purely for the sake of simplifying the Figure). It will be seen that in this case, there is no control signal from the LG lever assembly 24 to the CPM 22. In this embodiment, the CPM 22 receives the UP or DOWN command from the LGLCU 42. The LGLCU thus receives the take-off confirmation from the TODS 46, detects when the LG lever reaches an UP or DOWN position (whether automatically or manually or a combination of the two) and controls the operation of the motor 40.

[0038] FIG. 8 shows a third embodiment, using the same reference numerals as FIG. 7. Only the significant differences will now be described. It will be seen that in this case, that there is no separate LGLCU and instead control of the LG lever assembly 24 is performed entirely by the CPM 22. Thus, in this embodiment, the CPM 22 receives the UP or DOWN command from the LG lever assembly 24, receives the take-off confirmation from the TODS 46, detects when the LG lever reaches an UP or DOWN position (whether automatically or manually or a combination of the two) and controls the operation of the motor 40.

[0039] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein.

[0040] The control systems needed to operate the LG retraction and to control the automated movement of the pilot's LG lever in the cockpit could be provided in any number of different ways. The embodiments could also similar provide automated LG deployment, at a suitable moment before landing, by means of automatically moving the LG lever in a manner that could be overridden by the pilot.

[0041] It will be appreciated that two levers may alternatively be provided one for initiating a DOWN instruction and the other for initiating an UP instruction.

[0042] In the Figures, the LG lever is shown to be automatically moveable by a motor, which has the appearance of a rotary motor. It will be appreciated that a linear actuator, a different prime mover device, or other types of apparatus for causing movement could instead be used.

[0043] It may be that the LG lever housing contains the LG lever control unit (LGLCU).

[0044] It may be that the function of the CPM, LGLCU and/or the TODS could be combined into one computer processing unit. For example, some or all of the functionality of the TODS could be provided as part of the CPM in the embodiment shown in FIG. 8.

[0045] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments. The term or shall be interpreted as and/or unless the context requires otherwise.