AIRCRAFT SUBSYSTEMS

[0001] This invention relates to computer based functional testing of one or more aircraft subsystems residing at remote locations relative to a system test unit. The present invention is particularly useful for, but not necessarily limited to, testing aircraft subsystems before aircraft assembly and testing replacement aircraft subsystems during maintenance or repair.

BACKGROUND

[0002] Functionally testing aircraft subsystems in test rigs before both aircraft assembly and during maintenance and repair is an essential requirement for both commercial and military aircraft. Such functional testing can significantly reduce costs since a subsystem can be tested without first being installed in an aircraft and later having to be replaced if it was determined to be faulty shortly after installation.

[0003] Aircraft subsystems are often manufactured at remote locations away from a manufacturing or maintenance facility. For instance, during the process of aircraft assembly/manufacture, aircraft subsystems are often sourced from numerous suppliers that may be located in different regions or countries. The suppliers therefore functionally test the subsystem to be supplied in a test rig in which moving components of the subsystem are actuated and move through their ranges to simulate actual operation during normal use. However, because each remotely located subsystem is typically tested in isolation with respect to some or all of the other subsystems of the aircraft, there is a possibility that, due to manufacturing tolerances or software errors, the subsystems will not work as required and are identified as incompatible or faulty when the aircraft is assembled. As a result, significant manufacturing assembly/manufacturing delays and additional costs may occur as the incompatible or faulty subsystem needs to be removed from the aircraft and replaced with other re-ordered subsystems which can only be determined as compatible or fault free when installed or tested at the point of installation.

[0004] To alleviate the above problem, groups of aircraft subsystems are often tested together in test rigs at a central testing location. However, identified incompatible or faulty subsystems still have to be re-ordered which can be a costly and time consuming process. Furthermore, during maintenance and repair, replacement subsystems may be

incompatible or faulty when the installed on an aircraft thus significantly increasing aircraft down-time. [0005] It is an object of embodiments of the invention to at least mitigate one or more of the problems associated with testing of aircraft subsystems.

BRIEF SUMMARY OF THE DISCLOSURE

[0006] In accordance with the present invention there is provided a computer based test system for functionally testing aircraft subsystems, the test system comprising: a system test unit that includes a plurality of test unit interfaces and at least one of the test unit interfaces has a communications protocol converter; a plurality of test rig assemblies including a remote test rig assembly and a second test rig assembly, the remote test rig assembly being at a location remote from both the system test unit and the second test rig assembly, and each of the test rig assemblies includes a test rig with an operational aircraft subsystem mounted thereto and a test rig assembly interface coupled to a respective one of the test unit interfaces, and said test rig assembly interface of the remote test rig assembly includes a said communications protocol converter, wherein the system test unit is configured to provide aircraft simulation commands to the test unit interfaces over respective communications connections and in response to the commands receive status signals from the test rig assembly interfaces, and wherein the aircraft simulation commands and the status signals are in a first protocol that is converted to a second protocol by a respective said communications protocol converter.

[0007] In accordance with the present invention there is also provided a method of functionally testing aircraft subsystems, the method comprising: providing a system test unit that includes a plurality of test unit interfaces and at least one of the test unit interfaces has a communications protocol converter; selecting a plurality of test rig assemblies including a remote test rig assembly and a second test rig assembly, the remote test rig assembly being at a location remote from both the system test unit and the second test rig assembly, and each of the test rig assemblies includes a test rig with an operational aircraft subsystem mounted thereto and a test rig assembly interface for coupling to one of the test unit interfaces, and said test rig assembly interface of the remote test rig assembly includes a said communications protocol converter; coupling each said test rig assembly interfaces to a designated one of the test unit interfaces by respective communications connections; providing aircraft simulation commands to the test unit interfaces; receiving status signals from the test rig assembly interfaces, the receiving being in response to the commands; and outputting results based on the received status signals, wherein the aircraft simulation commands and the status signals are in a first protocol that is converted to a second protocol by the communications protocol converter for transmission over a respective one of the communications connections. [0008] In accordance with the present invention there is also provided a method of functionally testing aircraft subsystems, the method comprising: providing a system test unit that includes a plurality of test unit interfaces and at least one of the test unit interfaces has a communications protocol converter; selecting a plurality of test rig assemblies at least one of which is a remote test rig assembly at a location remote from the system test unit, and each of the test rig assemblies includes a test rig with an operational aircraft subsystem mounted thereto and a test rig assembly interface coupled to one of the test unit interfaces, and said test rig assembly interface of the remote test rig assembly includes a said communications protocol converter; coupling each said test rig assembly interfaces to a designated one of the test unit interfaces; providing aircraft simulation commands to the test unit interfaces; receiving status signals from the test rig assembly interfaces, the receiving being in response to the commands; determining, based on the received status signals, if the operational aircraft subsystem of the remote test rig assembly meets a defined set of functional test criterion.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a schematic block diagram of a computer based test system for functionally testing aircraft subsystems, according to an embodiment of the invention;

Figure 2 is a schematic block diagram of the system test unit of Figure 1 , according to an embodiment of the invention;

Figure 3 is a schematic block diagram of a computer based test system for functionally testing aircraft subsystems, according to another embodiment of the invention;

Figure 4 is a schematic block diagram of a system test unit of Figure 1 , according to a further embodiment of the invention;

Figure 5 is a schematic block diagram of a test rig assembly, according to an embodiment of the invention; and

Figure 6 is a flow diagram illustrating a method of functionally testing aircraft subsystems according to an embodiment of the invention.

DETAILED DESCRIPTION

[0010] Referring to figure 1 there is illustrated a schematic block diagram of a computer based test system 100 for functionally testing aircraft subsystems, according to an embodiment of the invention. The computer based test system 100 comprises a system test unit 102 that includes a plurality of test unit interfaces 104A to 1 04D, at least one of which (i.e. interface 104C) has a communications protocol converter 106A. In this embodiment the system 100 includes a plurality of test rig assemblies 1 10A to 1 1 OC, one of which is a remote test rig assembly 1 1 0C that is at a location remote from the system test unit 102.

[001 1] Each of the test rig assemblies 1 10A to 1 10C includes a test rig 108 to which is mounted an operational aircraft subsystem 1 1 2. Each aircraft subsystem 1 12 is part of, or is a complete, aircraft subsystem examples of which include: an aircraft hydraulics system, an aircraft engine or aircraft engine system, an aircraft fuel system, an aircraft landing gear system, an aircraft flap control system, an aircraft electricity generating system, an aircraft navigation system, and an aircraft cabin climate control system.

[0012] Each test rig assembly 1 10A to 1 10C includes a respective test rig assembly interface 1 14A to1 14C coupled to a respective one of the test unit interfaces 104A to 104C. In this embodiment, the test rig assembly interfacel 14C of the remote test rig assembly 1 10C includes a communications protocol converter 106B. For convenience and efficiency, the remote test rig assembly 1 10C is located proximal to a place of assembly of the associated operational aircraft subsystem 1 12 that forms part of the test rig assembly 1 10C. As shown, in this embodiment each test rig interface 1 14A to1 14C includes, or is coupled to, an aircraft subsystem interface 1 20 that forms part of the respective aircraft subsystem 1 12 of a respective test rig assembly 1 1 0A to 1 1 OC. In addition, although not shown, it will be apparent to a person skilled in the art that one or more of the respective test rig assemblies 1 1 0A to 1 10C may have sensors mounted on their respective test rig 108. These sensors monitor movement of components of the aircraft subsystems 1 12 to thereby create the status signals that are sent to the system test unit 102.

[0013] The computer based test system 100 includes communications connections 1 16A to 1 16D in which connection 1 16A coupes test rig assembly interface 1 14A to test unit interfaces 104A, connection 1 16B coupes test rig assembly interface 1 14B to test unit interfaces 104B and connection 1 16C coupes test rig assembly interface 1 14C to test unit interfaces 104C. In this particular embodiment the test rig assembly interface 1 14C includes an aircraft subsystem interface 120 and internal communications connection 1 18 that couples the aircraft subsystem interface 120 to the communications protocol converter 106B. It should be noted that in order to determine if each aircraft subsystem 1 1 2 is functioning in a manner that is compatible with and meets the tolerances required by other subsystems on a complete aircraft, each aircraft subsystem 1 12 in the test system 100 is designated and intended for use on a same aircraft. [0014] In this embodiment the system test unit 102 is coupled to an avionic control system 124 of an aircraft by the test unit interfaces 104D and the communications connection 1 16D. As will be apparent to a person skilled in the art, the communications connection 1 16D includes a bus architecture as do communications connections 1 16A, 1 16B and 1 18. In contrast the communications connection 1 16C is typically an internet connection medium such as an Ethernet or radio link.

[0015] The system test unit 102 is configured to provide aircraft simulation commands to the test unit interfaces 104A to 104C and, in response to the commands, receive status signals from the test rig assembly interfaces 1 14A to 1 14C. In this particular embodiment, the aircraft simulation commands are provided by the avionic control system 124 and the avionic control system 124 also provides further commands after processing the status signals from the test rig interfaces 1 14A to 1 14C.

[0016] In this embodiment the test rig assembly 1 10C is a remote test rig assembly and assembly 1 10A is a second test rig assembly. The remote test rig assembly 1 10C is at a location remote from both the system test unit 102 and the second test rig assembly 1 10A. Furthermore, the remote test rig assembly 1 10C is typically located proximal to a place of assembly of its associated operational aircraft subsystem 1 12. In this context remote location means in another building, suburb, town, city, country, state or country.

[0017] In operation, the aircraft simulation commands and status signals are in a first protocol that is converted to a second protocol by the communications protocol converters 106A and 106B. This conversion is because the communications connection 1 16C is an internet connection medium, and transmission of data along this medium requires conversion to and from the protocol used by the bus architecture of the avionic control system 124. For instance, in one embodiment the aircraft simulation commands are sent to the communications protocol converter 106A in the first protocol, which is a system format/protocol (P1 ), used by the avionic control system 124 of the aircraft for which the subsystems 1 12 are intended. The system format/protocol (P1 ) of the aircraft simulation commands is converted by the communications protocol converter 106A into the second protocol, which is a transmission format/protocol (P2), and is sent along the

communications connection 1 16C. This transmission format/protocol (P2) is typically in an Internet communication Protocol such as a packet protocol format which includes an internet address of the test rig assembly interface 1 14C.

[0018] The communications protocol converter 106B of the test rig assembly interface 1 14C converts the aircraft simulation commands in the transmission format/protocol (P2) back into the system format/protocol (P1 ). The converted commands in the system format/protocol (P1 ) are then sent to the aircraft subsystem interface 120, of the subsystem 1 12 of the test rig assembly 1 10C, through communications connection 1 18. Similarly, status signals in a system format/protocol (P1 ) that are generated by the test rig assembly 1 10C, are converted by the communications protocol converter 106B into the transmission format/protocol (P2). The status signals in the transmission format/protocol (P2) are along communications connections 1 16C to the test unit interface 104C. The communications protocol converter 106A of the test unit interface 104C converts the aircraft simulation commands in the transmission format/protocol (P2) back into the system format/protocol (P1 ) for processing by the avionic control system 124.

[0019] Referring to figure 2 there is illustrated a schematic block diagram of the system test unit 102, according to an embodiment of the invention. The system test unit 102 includes a processor 202 and aircraft system bus 204 coupling the processor 202 to the avionic control system 124 via the test unit interfacel 04D. The system test unit 102 also includes a Read Only Memory (ROM) 206, a Random Access Memory (RAM) 208 and an operator interface 210 all of which are coupled to the processor 202 by a common bus 212. In this embodiment, both the aircraft system bus 204 and the common bus 212 include address and data lines as will be apparent to a person skilled in the art.

[0020] The RAM 208 in use provides for storing simulation test data resulting from the aircraft simulation commands and the status signals which can be accessed via the operator interface 210. Furthermore, the operator interface 210 can communicate with the processor 202 to select aircraft simulation commands, routines or programs stored in the ROM 206. These aircraft simulation commands, routines or programs are executed by the processor 202 by communicating with the test rig assemblies 1 10A to 1 10C and avionic control system 124. Hence, the operator interface 210 can be used to select a flight simulation routine and, because of the need to convert the commands and status signals between protocols P1 and P2, the flight simulation is a non-real time simulation.

[0021] Referring to figure 3 there is illustrated a schematic block diagram of a computer based test system 300 for functionally testing aircraft subsystems, according to another embodiment of the invention. The system 300 is similar to that of the system 300 and to avoid repetition only the differences will be described. In this embodiment each of the test unit interfaces 104A to 104C has a respective communications protocol converter 106C, 106E, 106A and each of the test rig interface 1 14A to1 14C includes a respective communications protocol converter 106D, 106F and 106B. Each test rig interface 1 14A to1 14C also includes an aircraft subsystem interface 120 and internal communications connections 1 18. It will therefore be apparent that the respective connections 1 16A to 1 16C between the test rig interfaces 1 14A to1 14C and test unit interfaces 104A to 104C are typically internet connection mediums such as an Ethernet or radio links.

[0022] In this embodiment the test rig assembly 1 10C is a remote test rig assembly and assembly 1 10A is a second test rig assembly. The remote test rig assembly 1 10C is at a location remote from both the system test unit 102 and the second test rig assembly 1 10A. As shown, remote test rig assembly 1 10C and is typically located proximal to a place of assembly of its associated operational aircraft subsystem 1 12. Also the second test rig assembly 1 10A and assembly 1 10B is at a location remote from both the system test unit 102 and may also be at locations remote from each other such as a place of assembly of their associated operational aircraft subsystem 1 12. Again, in this context remote location means in a different building, town, city, country, state or country.

[0023] Also, in this particular embodiment, the aircraft simulation commands are provided by the avionic control system 124 and the avionic control system 124 also provides further commands after processing the status signals from the test rig interfaces 1 14A .0 1 14C.

[0024] In operation, the aircraft simulation commands and status signals are in a first protocol that is converted to a second protocol by the respective communications protocol converters 106A to106F. This conversion is because the communications connections 1 16A to 1 16C are internet connection mediums, and transmission of data along this medium requires conversion to and from the protocol used by the bus architecture of the avionic control system 124. Thus, similar to the test system 100, the aircraft simulation commands are sent to the communications protocol converters 106A, 106C and 106E in the first system format/protocol (P1 ). The system format/protocol (P1 ) of the aircraft simulation commands is converted, as required, by the respective communications protocol converters 106A, 106C and 106E into the transmission format/protocol (P2), and is sent along the respective communications connections 1 16A to 1 16C.

[0025] The communications protocol converters 106B, 106D and 106F, when necessary, converts the aircraft simulation commands in the transmission format/protocol (P2) back into the system format/protocol (P1 ). The converted commands in the system

format/protocol (P1 ) are then sent to the associated aircraft subsystem interface 120. Similarly, status signals in a system format/protocol (P1 ) that are generated by the test rigs and are converted by the respective communications protocol converters 106B, 106D and 106F into the transmission format/protocol (P2). The status signals in the transmission format/protocol (P2) are sent along communications connections to the respective test unit interfaces 104A to 104C. The communications protocol converters 106A to 106C convert the aircraft simulation commands in the transmission format/protocol (P2) back into the system format/protocol (P1 ) for processing by the avionic control system 124.

[0026] Referring to figure 4 there is illustrated a schematic block diagram a system test unit 400, according to a further embodiment of the invention. The system test unit 400 includes a Read Only Memory (ROM) 406, a Random Access Memory (RAM) 408 and an operator interface 410 all of which are coupled to a processor 402 by a common bus 412. In this embodiment the common bus 412 includes both address and data lines as will be apparent to a person skilled in the art.

[0027] Typically, the code stored in the ROM 406, which is executed by the processor 402, emulate the avionic control system 124 of an aircraft. Also, the RAM 408 in use provides for storing simulation test data resulting from the aircraft simulation commands and the status signals which can be accessed via the operator interface 410. Furthermore, the operator interface 410 can communicate with the processor 402 to select aircraft simulation commands, routines or programs stored in the ROM 406. These aircraft simulation commands, routines or programs are executed by the processor by

communicating with the test rig assemblies 1 10A to 1 10C. Hence, the operator interface 410 can be used to select a flight simulation routine and, because of the need to convert the commands and status signals between protocols P1 and P2, the flight simulation is a non-real time simulation. It will be apparent that, if required, all or many of the test unit interfaces 104A to 104C may include a communications protocol converter 106A for communicating with remote test rig assemblies.

[0028] In Figure 5 there is illustrated a schematic block diagram of a test rig assembly 500, according to an embodiment of the invention. The test rig assembly 500 can replace any or all of the test rig assemblies 1 10A to 1 10C of the test systems 100 or 300. The test rig assembly 500 includes a test rig assembly interface 514 for coupling to a respective one of the test unit interfaces 104A to 104C via one of the communications connections 1 16A to 1 16C that are typically an internet connection medium such as an Ethernet or radio link. In this embodiment, the test rig assembly interface 514 includes a

communications protocol converter 506A. Also, the operational aircraft subsystem 1 12, that forms part of the assembly 500, has an aircraft subsystem interface 120 with an integral communications protocol converter 506B.

[0029] There are sensors 520 mounted on the test rig 108 and these sensors monitor movement of components of the aircraft subsystems 1 12 to thereby create the status signals that are sent to the system test unit 102. There is also a rig operator interface 530 coupled to a control unit 530. The a control unit 530 is coupled to communicate with the system test unit 102 and allows a rig operator to set parameters read data and send data and instructions to the system test unit 102.

[0030] As will be apparent to a person skilled the art, the test rig assemblies 1 10A to 1 10C may also include a rig operator interface and control unit 530 which typically has a display screen such as a touch screen. Furthermore, all of the above test rig assemblies have an integrated electric power source for supplying power to at least their respective operational aircraft subsystem 1 12.

[0031] Referring to figure 6 there is illustrated a flow diagram illustrating a method 600 of functionally testing aircraft subsystems according to an embodiment of the invention. By way of explanation only, the method 600 will be primarily described with reference to the system computer based test system 100. The method 600, at a block 610, selects, identifies, assigns, locates or provides the system test unit 102 which is typically located near an aircraft assembly or maintenance facility. At a block 615, the required test rig assemblies 1 10A to 1 10C are selected and set up (and optionally calibrated) and at a block 620 each of the selected test rig assembly interfaces 1 14A to 1 14C are coupled to a designated one of the test unit interfaces 104A to 104C. There is then performed, at a block 620, a process of providing aircraft simulation commands to the test unit interfaces 104A to 104C. These commands are stored in a simulation programs stored in the ROM 206 and are received by any one of the relevant test rig assembly interfaces 1 14A to 1 14C thereby selectively actuating one or more operational aircraft subsystems 1 12.

[0032] In response to commands, the actuation of an associated operational aircraft subsystem 1 12 is performed. Consequently, the sensors on an associated test rig assembly therefore create status signals and at a block 625 the method 600 receives status signals from the test rig assembly interfaces 1 14A to 1 14C. At a block 635 the method outputs test results to the operator interface of the system 100 or to any other output means for analysis. These test results are based on the received status signals, and determine if the operational aircraft subsystem of, for instance, the remote test rig assembly meets a defined set of functional test criterion. In one embodiment the method 600 may be used to functionally test an operational aircraft subsystem 1 12 mounted to a remote test rig 108 to thus determine if the operational aircraft subsystem 1 12 can be used as a replacement for a faulty aircraft subsystem on an aircraft. If the operational aircraft subsystem meets a defined set of functional test criterion then it can be shipped for installation on the aircraft.

[0033] Advantageously, the invention provides for testing operational aircraft subsystems prior to assembly and prior to every subsystem being located in a common central location. The invention allows for the testing remotely located components and subsystems that comprise the various systems of an aircraft. Incompatible or faulty subsystems or components can therefore be identified before shipping to the common central location thus eliminating or at least alleviating the need to replace faulty shipped subsystems or components.

[0034] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of them mean "including but not limited to", and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. Also, although three test rig assemblies have been illustrated many more such test rig assemblies may be include in the system and method as described herein.

[0035] Features, integers, characteristics, compounds, or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.