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(11) | EP 0 121 624 A2 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Aircraft maintenance |
| (57) To speed turn around of an aircraft, it is provided with a maintenance data terminal
(5) including a subsidiary computer (6) arranged to receive fault and aircraft state
information from the main aircraft computer(s) (2) and other on- board equipment and
further including a keyboard (8) and alphanumeric display (7) controlled by and controlling
the subsidiary computer (6) to display logged faults, run test sequences, give step-by-step
maintenance information and so on, the terminal (5) being fitted to the aircraft with
at least the keyboard (8) and the display (7) behind a removable body panel (10),
so as to be easily accessible to a ground crew. |
[0001] The efficient operation of aircraft, both civil and military, depends to some extent on the speed and efficiency of maintenance or 'turn-around' of those aircraft, particularly when deployed at an outstation airfield where the ground crew may be unfamiliar with the type of aircraft.
[0002] According to this invention, there is provided an aircraft in which there is installed, at a position accessible to a ground crew, a maintenance data terminal including an alphanumeric display unit for providing maintenance information to said ground crew, switch means for enabling the ground crew to control the information displayed, and a panel control computer system which is connected to said display unit, said switch means and to at least one further computer system on board the aircraft, and which is operable, during flight of the aircraft, for receiving information available from said further computer system, for comparing that information with fixed information held by the panel control computer system and thereby logging aircraft faults occurring during flight, said panel control computer system being further operable, while the aircraft is on the ground, for causing the display unit to display information about those faults, and also to display state information concerning the aircraft including replenishment requirements for materials, such as fuel, which are used up during flight.
[0003] Advantageously, said terminal is fitted to the aircraft behind a door or removable body panel at a position easily available to ground crew outside the aircraft. The display unit preferably comprises a light-emitting diode matrix display while the switch means may comprise a series of labelled illuminated push-button switches.
[0004] For a better understanding of the invention reference will be made, by way of example to the accompanying drawing in which:-
Figure 1 is a diagrammatic view of part of an aircraft including a maintenance data terminal, and
Figure 2 is a more detailed view of a display panel and keyboard used in the maintenance data terminal.
[0005] The aircraft shown comprises, as part of its normal equipment, a radar unit 1 and a computer system 2 connected by way of a data highway 3 to various sub-systems (not shown) on board the aircraft. By way of example, these sub-systems include various transducers for measuring operating states of the aircraft, the levels of fuel in the fuel tanks, engine testing transducers, hydraulic system fluid sensors and so on, along with devices for say recording the number of times that the aircraft undercarriage has operated, the cumulative operational time of the aircraft engines and so on. In addition, the sub-systems include a series of valves for controlling the distribution of fuel to the various fuel tanks on board the aircraft and an arrangement for interacting with ground refuelling apparatus to halt refuelling when the computer 2 determines that it has received sufficient fuel.
[0006] Connected to the computer system 2 by way of a serial data line 4, or as an alternative (not shown) connected in the form of a sub-system to the data highway 3, is a maintenance data terminal 5 which comprises a microprocessor based computer system 6 connected to an alphanumeric display unit 7 formed of a matrix of light-emitting diodes (not separately visible in detail) and to a keyboard 8 comprising twelve push-button switches 9, each of which is the kind having two labels with respective label illuminating lamps whereby, by switching on one or the other lamp, the apparent function of the button changes. The display unit 7 and keyboard 8 are installed behind a door or removable panel 10 at a position in the aircraft body 11 where it is reasonably easily accessible to a ground crew outside the aircraft. Naturally, the chosen position will depend on the type of aircraft - the position illustrated is given only by way of example. The computer system 6 includes a conventional arrangement of a microprocessor interconnected with some random access memory (RAM), some read-only memory (ROM) and some electrically eraseable read-only memory (EAROM).
[0007] The labels on the twelve push-buttons which labels include standard abbreviations known to those in the aircraft art, and the meanings thereof are as follows (note, of course, that only one label on each button is illuminated at any one time).
[0008] The function of the maintenance data terminal 5 is to communicate, in a well understood proper language or at least by well recognised abbreviations, the state of the aircraft, for example with regards to replenishment (fuel, hydraulic fluid, liquid oxygen) and also system faults down to line replaceable unit level, these to include accumulated time of operation of lifed items such as auxilliary power unit and air turbine motors and accumulated cyclic operations of equipment such as the undercarriage. The unit is preferably also able to initiate and display results of system built-in-tests (SBIT).
[0009] It is possible that ground crews maintaining the aircraft at forward airfields would not have access to maintenance manuals and therefore the panel operation, by design, is preferably capable of leading the ground crew through the correct operating sequence for the particular task in hand.
[0010] The vast majority of information processed by the maintenance data terminal is in the form of 16 bit digital data words derived from the aircraft data highway or received directly therefrom if the terminal is arranged as a sub-system as described earlier. Output of data from the terminal to the computer 2 (or to the highway 3) is restricted to the period whilst the aircraft is on the ground.
[0011] Bus traffic on the highway is of a cyclic nature and therefore each sub-system is allocated a 16 bit 'status good' data word and each line replacable unit on the system a 16 bit fault code. Transmissions to the terminal 15 during the flight phase are limited to system status including one 16 bit word for each of the aircraft sub-systems. On an operational aircraft the 16 bit 'status good' word would be transmitted for each sub-system. These would be superceded by fault codes as and when line replaceable unit faults occur.
[0012] Status data on each sub-system is transmitted to the terminal 5 cyclicly and is initially deposited in RAM sub addressee. This is then compared with data in ROM look-up tables to determine the nature of the data (either status good or fault code). If this word is either a status good word or a fault code received previously then the information is ignored. A new fault code however is transferred to EAROM for later display on interrogation by the ground crew. A time-into-time mission tag is appended to each EAROM fault code.
[0013] Only in the ground mode is the terminal able to output requests to the aircraft data highway.
[0014] These will be addressed to the particular aircraft sub-system containing consumable items and these requests will be for actual contents. This data will again be deposited in RAM sub addresses and, after comparison with the look-up tables in ROM, will be displayed on the alphanumeric display.
[0015] Requests may also be made from the panel for individual sub-systems to carry out system built-in tests (SBIT s) and to report back system status.
[0016] If there are limitations on the non-volatile fault code storage in the EAROM, it may be desirable in order to meet conflicting terminal lifetime requirements to move data around instore periodically. For example, the operation of all the non-volatile store may be by moving the 25 sub addresses to a new location at the commencement of each mission.
[0017] The maintenance data terminal illustrated has been designed to provide all the information required to produce a rapid turn round of the aircraft. To meet this requirement with unfamiliar ground crews and the lack of an operations manual, the panel itself is capable of leading the operator through a set sequence of operations to meet his requirements. This is achieved by only illuminating the pushbutton captions as and when that button becomes active i.e. after a choice of mode (REPLENISH, FAULT LOCATION or TEST) has been made only the caption for the next step in the sequence is illuminated with the possible exception of RESET,
[0019] Assuming that faults have been logged into memory on the previous mission on the opening of the access panel door the operator is confronted with the captions REP; TEST and the red FAULT caption. A selection can be made at this point and having made that selection the other captions are extinguished and the RESET caption illuminated. Continuous depression of the selected button will cause paging of the systems associated with that mode at 2 second intervals. These are presented in the windows of the system display. At the end of the paging sequence the display is extinguished and remains so until the button is released. On release of the button the three original captions re-illuminate. Release of the button during the paging sequence will cause a hold on the particular pushbutton associated with the next step in the sequence of the mode selected will illuminate,
[0020] Continuous depression of the button marked REP causes paging of systems requiring replenishment i.e. FUEL, LIQUID OXYGEN, HYD, FLUID, WINDSCREEN WASH etc. Taking FUEL system as an example a halt to paging on the fuel would cause the captions O - 9, FILL and ENTER to illuminate whilst the display will present FUEL, the actual quantity on board and, when selected and input by operation of the ENTER button, the required quantity. After entering the quantity the RESET button illuminates allowing a reselection to be made along with the captions EXT.L (meaning external left), WINGS, and so on.
[0021] On selection of distribution followed by ENTER, the RESET button is again illuminated allowing re or defuelling to commence. Following the operation of the START button this caption extinguishes, the actual contents display increments or decrements according to the fuel gauging system data received and the STOP caption illuminates. When the actual contents equals the required contents, or if re/defuelling is suspended either by a fault or operation of the stop button, the system display commences to flash on and off at 1 sec intervals.
[0022] Continuous depression of the FAULT button from the primary mode selection will cause paging of the faults received and stored by the terminal in chronological order again at 2 second intervals. Release of the button will cause a halt as in replenishment paging. The display for fault indication covers 'aircraft system', live replaceable units requiring replacement and time of failure. The time of failure display has three separate and distinct indications. A blank display indicates that the fault occurred during servicing or that the fault had been accepted for flight prior to the previous mission. An all zero time" display indicates that the fault occurred on taxi and an actual time display is the actual time from take-off that the fault code was received by the terminal.
[0023] During fault location a number of items of equipment may require replacement under the requirements of 'lifed items'. The display will show 'system' 'LRU', the actual quantity display will show the life limit. This display will also be shown during REP paging.
[0024] When interrupting fault paging on a lifed item the pushbutton caption either 'CLOCK' or 'TOTAL' is illuminated. Operation of the illuminated button will cause it to extinguish and the RESET to illuminate. The sequence follows with the illuminations of the captions ENTER and STOP. ENTER will cause the clock or total to be reset to zero. STOP will cause the re-illumination of CLOCK or TOTAL.
[0025] Operation of the TEST pushbutton will cause the paging of those systems which have system built-in-tests initiated from the terminal. Release of the button will cause an interruption to the automatic paging and the START button will illuminate. Depression of the START button will cause the terminal to output a test commence signal on the particular system displayed.
[0026] Whilst an SBIT test is in progress the system display will indicate the system under test, the required quantity will indicate TEST, and the LRU display will indicate IN PROGRESS. If at the end of the test the 'status good' data word is received from the system then the indication 'IN PROGRESS' changes to 'SERVICEABLE', should, however, and LRU fault code replace the 'status good' data word then the normal fault indications apply.
1. An aircraft in which there is installed, at a position accessible to a ground crew,
a maintenance data terminal (5) including an alphanumeric display unit (7) for providing
maintenance information to said ground crew, switch means (8, 9) for enabling the
ground crew to control the information displayed, and a panel control computer system
(6) which is connected to said display unit (7), said switch means (8, 9) and to at
least one further computer system (2) on board the aircraft, and which is operable,
during flight of the aircraft, for receiving information available from said further
computer system (2), for comparing that information with fixed information held by
the panel control computer system (6) and thereby logging aircraft faults occurring
during flight, said panel control computer system (6) being further operable, while
the aircraft is on the ground, for causing the display unit (7) to display information
about those faults, and also to display state information concerning the aircraft
including replenishment requirements for materials, such as fuel, which are used up
during flight.
2. An aircraft according to claim 1 wherein said display unit (7) comprises a light-emitting
diode matrix.
3. An aircraft according to claim 1 or 2, wherein said switch means includes a keyboard
(8) comprising an illuminated push-button switches (9) and wherein said panel control
computer system (6) is operable to control the illumination of the switches (9).
4. An aircraft according to any preceding claim wherein the panel control computer
system (6) is operable to cause the display of information leading said ground crew
step-by-step through predetermined maintenance procedures for the aircraft.