Abstract:
The present invention resides in a system, method and an article of manufacture for transmitting maintenance and diagnostic data from an aircraft. The system comprises an aircraft, a cellular infrastructures and a data reception unit. The aircraft has an avionics system and a communications unit. The avionics system comprises a plurality of line replaceable units, and the communications unit is connected to each line replaceable, unit. The cellular infrastructure is in communication with said communications unit after the aircraft has landed. The communication is initiated automatically upon the landing of the aircraft. The data reception unit is connected to the cellular infrastructure.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    This application is related to the commonly-assigned U.S. Pat. No. 6,181,990, entitled “AIRCRAFT FLIGHT DATA ACQUISITION AND TRANSMISSION SYSTEM,” issued on Jan. 30, 2001. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention is directed generally to an aircraft maintenance/diagnostic data transmission system and, more particularly, to on-board cellular data transmission/reception system in conjunction with maintenance/diagnostics data transmission over public telephone networks and the Internet.  
           [0004]    2. Description of the Related Art  
           [0005]    It is common for aircraft avionics and electronic engine control systems to require download of maintenance/diagnostic data for maintenance purposes. Presently, most aircraft utilized in passenger, freighter and business categories require some degree of diagnostic data download from one or more avionics and engine control equipment, such as an Electronic Engine Computer (EEC), Data Encryption Unit (DEU), Flight Management Computer (FMC), etc. These downloads are currently accomplished manually by connecting a download device to the aircraft, or using permanently installed maintenance/diagnostics terminals. The diagnostic information is transferred from the avionics equipment to storage media, such as floppy disks or CD-ROMs. Upon completion of the transfer from the avionics unit to the storage media, the maintenance/diagnostic information is transferred to the maintenance center of the airline for processing.  
           [0006]    The current manual download includes the human as an active component of this activity. The steps include the downloading to a media, delivery of the media to the maintenance facilities and transfer of the data from the media to a maintenance computer for analysis.  
           [0007]    Computer systems are typically used to analyze and manage the aircraft maintenance/diagnostics for the aircraft. Such systems require manual transportation of the down load media from each aircraft to the maintenance center.  
           [0008]    Often times, radio frequency (RF) transmissions are used to transmit maintenance/diagnostic data relating to an aircraft. This technique, however, requires substantial investments to construct the RF transmission systems required for such a system to work. Furthermore, it is very expensive to create redundancy in such a system.  
           [0009]    Maintenance/diagnostic data can also be transmitted to an aircraft via a telephone system located in a terminal. Such a system, however, requires that the aircraft be docked at the gate before transmission begins, thereby resulting in not being able to transfer uploads to aircraft that are routinely parked on the tarmac, away from the gates when loading and unloading passengers and cargo. Furthermore, such a system requires an added step of transmitting the download maintenance/diagnostic data from the telephone system to the maintenance center, increasing the cost of installing, operating, and maintaining such a system.  
           [0010]    Thus, there is a need for an aircraft maintenance/diagnostics download system that automatically transfers aircraft/engine and maintenance/diagnostic data to the airline&#39;s or operator&#39;s maintenance and engineering center with little or no human involvement, and which relies on a widely available and reliable public wireless, public switch telephone network (PSTN), integrated services digital network (ISDN), and/or Internet delivery systems.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention, which addresses this need, resides in a system, method and an article of manufacture for transmitting maintenance and diagnostic data from an aircraft.  
           [0012]    The system comprises an aircraft, a cellular infrastructures and a data reception unit. The aircraft has an avionics system and a communications unit. The avionics system comprises a plurality of line replaceable units. The communications unit is connected to each line replaceable unit. The cellular infrastructure is in communication with said communications unit after the aircraft has landed. The communication is initiated automatically upon the landing of the aircraft. The data reception unit is connected to the cellular infrastructure.  
           [0013]    The present invention represents a substantial advance over prior aircraft data download systems. For example, the present invention has the advantage that it requires little expense to implement because it uses well-known cellular technology, cellular infrastructure, telephone networks and computer networks, which are already in place. The present invention also has the advantage that it can transmit the diagnostic data over one or more channels to achieve the necessary transmission bandwidth and achieve a low data transmission time. The present invention has the further advantage that it does not require a dedicated data link between the aircraft and the airline/aircraft operator engineering center and/or an airport terminal. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0014]    For the present invention to be clearly understood and readily practiced, the present invention will be described in conjunction with the following figures, in which like reference numbers represent corresponding parts throughout:  
         [0015]    [0015]FIG. 1 illustrates an exemplary aircraft maintenance data download and transmission system, in accordance with an embodiment of the present invention;  
         [0016]    [0016]FIG. 2 is a block diagram illustrating a more detailed embodiment of the system illustrated in FIG. 1, in accordance with an embodiment of the present invention;  
         [0017]    [0017]FIG. 3 is a block diagram illustrating data flow through the system illustrated in FIG. 2, in accordance with an embodiment of the present invention;  
         [0018]    [0018]FIG. 4 is a flowchart illustrating a method carried out by the GroundLink processor in the aircraft, in accordance with an embodiment of the present invention;  
         [0019]    [0019]FIG. 5 is a flowchart illustrating a method of performing the start secondary data threads and transmitting data packet step  89  of FIG. 4, in accordance with an embodiment of the present invention;  
         [0020]    [0020]FIG. 6 is a flowchart illustrating a method of performing the start secondary data threads step  103  of FIG. 5, in accordance with an embodiment of the present invention;  
         [0021]    [0021]FIG. 7 is a flowchart illustrating a method of operating the GroundLink computer in the airlines/operators engineering center, in accordance with an embodiment of the present invention;  
         [0022]    [0022]FIG. 8 is a flowchart illustrating a method of performing the process end of session step  152  of FIG. 7, in accordance with an embodiment of the present invention;  
         [0023]    [0023]FIG. 9 is a block diagram illustrating another embodiment of the system illustrated in FIG. 1.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0024]    In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown only by way of illustration a specific embodiment in which the invention may be practiced. It is to be understood that other embodiments may be utilized and changes may be made without departing from scope of the present invention  
         [0025]    It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, other elements found in a typical communications system. It can be recognized that other elements are desirable and/or required to implement a device incorporating the present invention. For example, the details of the avionics and engine maintenance data download method, the cellular communications infrastructure, the Internet, and the public-switched telephone network are not disclosed. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein.  
         [0026]    [0026]FIG. 1 illustrates an exemplary aircraft transmission/reception of avionics and engine maintenance/diagnostic data download system  10 , in accordance with an embodiment of the present invention. An aircraft  12 , which has stored avionics and electronic engine control units maintenance/diagnostics data, is illustrated after landing. The aircraft  12  transmits maintenance/diagnostics data as cellular communications signals over a cellular infrastructure  14 . The cellular infrastructure  14  acts as a communications channel to the communications medium  16 . Airline/operators engineering center  18  is connected to the medium  16  by any conventional connectivity medium such as, for example, a leased line. Once the cellular connections are made via the medium  16  data can flow bidirectionally to and from the aircraft.  
         [0027]    [0027]FIG. 2 is a block diagram illustrating a more detailed embodiment of system  10  illustrated in FIG. 1, in accordance with an embodiment of the present invention. The aircraft  12  includes avionics system  55  having a suite (1 through N) of avionics (and electronic engine control) line replaceable units (LRU). Each avionics and electronic engine control line replaceable unit includes a storage media for storing maintenance/diagnostics data in a digital format.  
         [0028]    The maintenance/diagnostics data are transferred from the avionics and electronic engine control unit LRU  55  to the communications unit  26  via a bus  28 . The bus  28  is connected to an avionics I/O interface  30  in the communications unit  26 . The avionics I/O interface  30  can be a standard bus interface such as, for example, an ARINC  429  bus, RS-232/422 or Ethernet.  
         [0029]    The avionics I/O interface  30  is connected to a GroundLink processor  32 . The GroundLink processor  32  can be a general purpose processor such as a personal computer, a microprocessor such as an Intel Pentium.RTM processor, or a special purpose processor such as an application specific integrated circuit (ASIC) designed to operate in the system  10 . The GroundLink processor is connected to one or more cellular channels  36  via multi port serial card  34 .  
         [0030]    The GroundLink processor  32  is responsive to an engine shut-off (or equivalent) signal, which notifies the GroundLink processor  32  to initiate transmission of the data after the aircraft  12  has landed. Upon receipt of this signal, the processor  32  acquires the maintenance/diagnostic data from the avionics LRU  55  via the avionics I/O  30 , and transmits the data to a multi-port serial card  34 . Each I/O port of the card  34  is attached to a cellular channel  36  which can open, sustain, and close a physical, over-the-air, channel to the cellular infrastructure  14 . The cellular channels  36  can transmit and receive simultaneously and can thus transmit and receive data in parallel. Each cellular channel  36  is connected to an antenna matching network. One or more antennas  38  are installed in the aircraft  12  so as to optimize free space radiation to the cellular infrastructure  14 .  
         [0031]    The data are transmitted over cellular air link using the physical layer modulation of the cellular infrastructure  14 . The cellular infrastructure  14  includes an antenna  40 , which is within free-space radiating range of the aircraft  12 . The antenna  40  is connected to a cellular base station transceiver subsystem  42 . The subsystem  42  is connected to a cellular base station controller  44  which has a direct connection via a router (not shown) to the Internet  45 . The data is transmitted via the Internet  45  to the airline/operators engineering center  18 .  
         [0032]    A local router  46  in the airline/operators engineering center  18  is connected to the Internet  45 , such as via a connection to the backbone of the Internet  45 . The router  46  connects a local area network  48  to the Internet  45 . The local area network can be of any type of network such as, for example, a token ring network, an ATM network, or an Ethernet network. A GroundLink computer  50  is connected to the network  48  and receives the maintenance/diagnostics data from the specific aircraft tail number for storage in the attached storage unit  52  for analysis by related application programs. The storage unit  52  can be any type of unit capable of storing data such as, for example; disk drive or a disk array.  
         [0033]    Data transfer can also occur from airline/operators engineering center  18  to the aircraft  12 . The data are transmitted over the Internet  45  and cellular infrastructure  14  and received by antenna  38 . The serial card  34  receives the data from the cellular channels  38  and processor  32  outputs the data via the avionics I/O  30  to avionics  55  via bus  28 .  
         [0034]    [0034]FIG. 3 is a block diagram illustrating data flow through the system  10  illustrated in FIG. 2, in accordance with an embodiment of the present invention. The maintenance data files are stored by the avionics LRUs. An application layer  58  of an operating system  60  of the GroundLink processor  32  acquires, compresses, encrypts, and segments the data files. The operating system  60  can be any type of operating system suitable such as, for example, UNIX. A typical stored file may be compressed from approximately 1 Mbytes to approximately 100 Kbytes. Compression may be done by any compression method such as, for example, the method embodied in the PKZIP.RTM. compression utility, manufactured by PKWARE, Inc. Encryption can be accomplished using any suitable asymmetric (public key) or symmetric encryption method such as, for example, the method embodied in Data Encryption Software (DES), manufactured by American Software Engineering or the methods in the RC2, RC4, or RC5 encryption software manufactured by RSA Data Security, Inc. During segmentation, individual datagrams of, for example, 1024 bytes are formed and indexed for subsequent reassemble.  
         [0035]    The operating system  60  passes the datagrams to a network layer  62  which constructs UDP/IP packets from the datagrams by adding message headers to the datagrams. The network layer  62  then routes the packets to one of up to a fixed number (e.g., 16) peer-to-peer protocol (PPP) threads running within the operating system  60  at a data link layer interface  64 . The PPP convey the packets trough the multi port serial card  34  to the cellular channels  36 . The packets are routed through the cellular infrastructure  14  to the Internet  45 . The packets are received from the internet  45  by the local router  46  in the airline/operators engineering center  18 . The network layer  62  receives acknowledgments of received packets from the GroundLink computer  50  in the airline/operators engineering center  18 . The network layer  62  also re-queues packets that are dropped before reaching the GroundLink computer  50 .  
         [0036]    The local router  46  in the airline/operators engineering center  18  receives the packets and routes them to the GroundLink computer  50 . A local network interface  68  receives the packets and a data link layer interface  70  of an operating system  72  passes the packets to a network layer  74  of the operating system  72 . The operating system  72  can be any type of suitable operating system such as, for example Windows. The network layer  74  sends acknowledgements of successful packet deliveries to the GroundLink processor  32 . The network layer  74  also removes the UPD/IP headers and passes the datagrams to an application layer  76 . The application layer  76  reassembles, decrypts, and uncompresses the datagrams to restore the file to its original form. The application layer then passes the file  78  to the storage unit  52 . The functions performed by the aircraft  12  and the airline/operator engineering center  18  are similarly interchangeable when data is transferred from the airline/operator engineering center  18  to the aircraft  12 .  
         [0037]    [0037]FIG. 4 is a flowchart illustrating a method carried out by the GroundLink processor  32  in the aircraft, in accordance with an embodiment of the present invention. At step  81 , the GroundLink processor  32  receives a “engine shut-off’, or similar signal which indicates that data transmission process can be started and the GroundLink processor  32  initiates a data transfer by acquiring maintenance/diagnostics data files from avionics LRUs  55 . At step  83 , the application layer  58  compresses the acquired files and at step  84  it encrypts the file. At  86  the data is segmented into datagrams and UPD/IP packets are created and the packets are placed in a queue. The packets are ready for transmission over fixed number of threads, corresponding to the number of cellular channels  36 . At step  89 , the primary data thread is started to make the initial call and open the communications channel to the airline/operators engineering center  18 . There is a wait period, for example five seconds, inserted at step  91 , and the status of the threads is tested for active state at step  92 . If any thread is found active the process loops back to the wait state. If there are no active channels detected at step  92  this method exits at step  93 .  
         [0038]    [0038]FIG. 5 is a flowchart illustrating a method of performing the start primary data thread step  89  of FIG. 4, in accordance with an embodiment of the present invention. At step  100  point to point (PPP) connection is initiated. At step  102  the process session is initiated. The secondary data threads are opened at step  103 .  
         [0039]    At step  104 , it is determined if more packets are left to be transmitted. If so, the next packet in the data thread is transmitted at step  106  and the process loops back to step  104  to check if any more packet is available for transmission. If no packets are left to transmit, as determined at step  104 , the state of the data threads is checked at step  108 . If any data thread is found active at  108 , then the process returns to step  104  to see if more data is to be transmitted. If it is found at step  108  that there is no active data thread then the session is ended at step  110 . The PPP connections are closed at step  112  and the method exits at step  114 .  
         [0040]    [0040]FIG. 6 is a flowchart illustrating a method of starting secondary data threads of step  103  of FIG. 5, in accordance with an embodiment of the present invention. All the available secondary data threads are set active in step  118  by the data link interface  64 . At step  120  the point to point (PPP) connections are initiated for each secondary data thread through the cellular channels  36  by the data link layer  64 . At step  122  a test is made to determine if there are data packets for transmission. If packet is available, it is sent in step  124  to the GroundLink computer. If there is no more data packets to be sent, as determined in step  122 , the PPP connections are closed in step  126 . The thread is set inactive in step  128  and the thread exits at step  130 .  
         [0041]    [0041]FIG. 7 is a flowchart illustrating a method of operating the GroundLink computer  50  in the airline/operators engineering center  18 , in accordance with an embodiment of the present invention. In response to the call placed by the GroundLink processor  32  through the primary channel a socket is opened at step  132  by the operating system  72  in the computer  50  to receive messages transported across the Internet  45 . At step  134 , the computer  50  waits for a message from the Internet  45 . When an initiate session message is received as determined at step  136 , the application layer  76  allocates buffer space at step  138 , sends a session acknowledgement message at step  140  to the GroundLink processor  32  on the aircraft  12  and the method returns to wait for additional messages at step  134 . If the message received was a data packet, as determined at step  142 , the network layer  74  removes the UDP/IP header and copies the datagram to the buffer in step  144 . At step  146  the network layer  74  sends an acknowledge message to the GroundLink processor  32  on the aircraft  12 .  
         [0042]    If end session message is detected at step  148  the application layer  76  performs a process end session at step  152  and returns to wait for message step  134 .  
         [0043]    [0043]FIG. 8 is a flowchart illustrating the steps included in the end session process step  152  of FIG. 7, in accordance with an embodiment of the present invention. At step  160 , the checksum is computed by the application layer  76  for the received data to check the integrity of the data. The checksum is checked at step  162  and if it is found to be correct the GroundLink computer  50  saves the buffer to a temporary file at step  164 . The application layer  76  of the GroundLink computer  50  then decrypts the file at step  166  and uncompresses the file at step  168 . The uncompressed file  78  is stored at step  170  by the operating system  72  on storage unit  52 . The GroundLink computer  50  sends an end session acknowledge message to the GroundLink processor  32  on aircraft  12  at step  174  and at step  178  the flow returns to step  134  of FIG. 7. If the checksum is not correct, as determined at step  162 , the GroundLink computer  50  sends an unsuccessful end session message (Nack) at step  176 , which notifies the GroundLink processor  32  to re-send the data and the flow returns to step  134  of FIG. 7.  
         [0044]    [0044]FIG. 9 is a block diagram illustrating another embodiment of the system  10  illustrated in FIG. 1. The operation of the system  10  of FIG. 9 is similar to that described in conjunction with the system  10  of FIG. 2. However, the data that is transmitted by the GroundLink processor  32  via the cellular infrastructure  14  is routed by the public switched telephone network (PSTN)  210  to the modem bank  212 . A modem bank  212  transmits the data to the GroundLink computer  50  via the local router  46  and local network  48 . The modem bank  212  can have a modem dedicated to receive data from each one of the cellular channels  36 .  
         [0045]    While the present invention has been described in conjunction with preferred embodiments thereof, many modifications and variations will be apparent to those of ordinary skill in the art. For example, although the system has been described hereinabove as transferring data from the aircraft, the system can also be used to transfer data to the aircraft with no modifications in the system. Also, the system may be used to transmit data while the aircraft is in flight. Furthermore, the system may be used without encryption and without data compression prior to sending data. The foregoing description and the following claims are intended to cover all such modifications and variations.