Abstract:
A method for improving fuel economy on a passenger jet aircraft comprises automatically receiving a communication from the aircraft to a ground station comprising at least one subsystem operating parameter measured during the current flight, detecting whether the operating parameter meets predetermined criteria and, if the criteria are met, automatically sending a communication to indicate the aircraft&#39;s status for a next flight. If the criteria are not met, a status of the aircraft is automatically changed and a communication is sent. Other methods and systems are also described.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a bypass continuation of International Patent Application No. PCT/US2013/048673, filed Jun. 28, 2013, which in turn claims the benefit of U.S. Provisional Application No. 61/665,842, filed Jun. 28, 2012, and U.S. Provisional Application No. 61/785,915, filed Mar. 14, 2013, all of which are herein incorporated by reference in their entirety. 
     
    
     FIELD 
       [0002]    This application relates to passenger jet aircraft, and in particular, to systems and methods for improving the fuel economy and safety of such aircraft. 
       BACKGROUND 
       [0003]    Improving the fuel economy and safety of passenger jet aircraft continues to be very important to operating competitively in today&#39;s crowded transportation marketplace. Reducing fuel consumption while maintaining the same or similar levels of service lowers operating costs, consumes fewer resources and, in some cases, may extend the capabilities of the aircraft. 
         [0004]    In the case of non-redundant two-engine passenger jet aircraft, there is a class of long routes, referred to as “extended operations” (ETOPS) routes, that have conventionally required an auxiliary power unit to be run continuously (“Continuous Run”), in addition to the operation of both engines on 737 aircraft. An auxiliary power unit (APU) is a small gas turbine engine used to supply pneumatic power for various subsystems of the aircraft including starting the main turbine engines, as well as supplying electrical power. If the APU is on Continuous Run status (APUCR), the APU consumes fuel and wear and tear on the APU is increased, thus detracting from the overall efficiency of the aircraft. By contrast, if the APU is not run continuously, or is only run when needed, which is referred to as “On Demand” (APUOD) status, the APU consumes far less fuel and wear and tear is reduced, thus improving the overall economy of the aircraft. 
         [0005]    It would be desirable to provide a robust approach for operating the APU only when required, such as to provide backup electrical in the event of a generator, or an engine failure. 
       SUMMARY 
       [0006]    Described below are systems and methods for improving passenger jet aircraft fuel economy that address some of the shortcomings of the prior art. 
         [0007]    According to a first implementation, a method for improving fuel economy on a passenger jet aircraft comprises automatically receiving a communication from the aircraft to a ground station comprising at least one subsystem operating parameter measured during the current flight, detecting whether the operating parameter meets predetermined criteria and, if the criteria are met, automatically sending a communication to indicate the aircraft&#39;s status for a next flight. If the criteria are not met, a status of the aircraft is automatically changed and a communication is sent. 
         [0008]    The method can comprise automatically updating the system to reflect the status of the aircraft. The method can comprise coordinating completion of any maintenance on the subsystem to automatically trigger resumption of a programmed maintenance routine. The aircraft subsystem can be an auxiliary power unit, and the detected parameter can be the exhaust gas temperature value of the auxiliary power unit. The aircraft&#39;s status for a next flight can comprise one of operating an auxiliary power unit on an on demand status or operating the auxiliary power unit continuously. 
         [0009]    The method can comprise detecting whether the operating parameter meets predetermined criteria, e.g., comprising determining whether the exhaust gas temperature value of the auxiliary power unit exceeds a threshold temperature. If the exhaust gas temperature value meets or exceeds a threshold temperature, then a communication can be initiated and the aircraft&#39;s status can be automatically updated in the system. 
         [0010]    The threshold temperature can be a first threshold temperature, and a first alert can be communicated, and the method can further comprise detecting whether the exhaust gas temperature value meets or exceeds a second threshold temperature higher than the first threshold temperature. If the second threshold temperature is met or exceeded, then a second alert can be communicated. 
         [0011]    According to a second implementation, a method for improving fuel economy on a passenger jet aircraft comprises receiving an exhaust gas temperature value for an axillary power unit on the aircraft, performing a comparison between the exhaust gas temperature value of the auxiliary power unit and at least one predetermined threshold temperature and determining, on the basis of the comparison, whether the auxiliary power unit must be operated continuously on the aircraft&#39;s next flight. 
         [0012]    Performing the comparison can comprise determining whether the exhaust gas temperature value of the auxiliary power unit meets or exceeds 593° C. In addition, the comparison can comprising determining whether the exhaust gas temperature valve of the auxiliary power units meets or exceeds 604° C. Further, the comparison can comprise determining whether the exhaust gas temperature value of the auxiliary power unit meets or exceeds 632° C. 
         [0013]    According to some implementations, performing a comparison comprises determining whether the exhaust gas temperature value of the auxiliary power unit is at least 593° C. and less than 604° C., and if so, sending a communication identifying the aircraft and the exhaust gas temperature value. 
         [0014]    Performing a comparison can comprise determining whether the exhaust gas temperature value of the auxiliary power unit is at least 604° C. and not greater than 632° C., and if so then sending a communication to identify the aircraft and the exhaust gas temperature value and automatically updating the system to reflect the aircraft&#39;s status as requiring the auxiliary power unit to be operated continuously on a next extended operations flight unless corrective action is taken. 
         [0015]    Performing a comparison can comprise determining whether the exhaust gas temperature value of the auxiliary power unit exceeds 632° C., and if so then sending a communication to identify the aircraft and the exhaust gas temperature value and automatically updating the system to reflect the aircraft&#39;s status as restricted from extended operations until corrective action is taken. 
         [0016]    Detecting an exhaust gas temperature value of the auxiliary power unit can occur while the aircraft is in flight and undergoing a cold soak start test. If at least one of an in-flight auxiliary power unit start and a cold soak start test is unsuccessful, then a communication can be sent and the system can be updated. The method can comprise conducting a test to determine if the auxiliary power unit operates normally on the ground. 
         [0017]    An aircraft maintenance verification system for a fleet of aircraft comprises a controller, a memory linked to the controller and having stored aircraft status information for each aircraft in the fleet and a display linked to the controller and the memory. The controller can be programmed to receive a predetermined subset of routine data transmitted from an aircraft in operation to a ground station, to send a normal operation communication indicating that the system is operating normally, and to update the display. If the normal operation communication is not received within a predetermined time period, an alert can be sent and the display can be updated. If the system is not returned to normal operation within a predetermined time interval, the system is updated to change the status of the aircraft. The subset of routine data received by the controller can include one or more parameters indicating the status of an auxiliary power unit. If the normal operation communication is not received, the system can be updated to require Continuous Run of the auxiliary power unit in each aircraft of the fleet. 
         [0018]    According to another implementation, a method for coordinating maintenance requirements for a fleet of aircraft comprises scheduling at least a first aircraft of the fleet for a routine in-flight test on a first date to occur on a qualifying flight within a predetermined interval, automatically updating the system at least once to reflect the status of the aircraft as the end of the pre-determined interval approaches and, if the aircraft is later subjected to other maintenance requirements, automatically updating the routine in-flight test from the first date to occur on a second date and updating the system. 
         [0019]    The foregoing and other objects, features, and advantages of the invention will become more apparent from the following detailed description, which proceeds with reference to the accompanying figures. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]      FIG. 1  is a flowchart of a first representative method for increasing aircraft fuel efficiency. 
           [0021]      FIG. 2  is a flowchart of a second representative method for increasing aircraft fuel efficiency. 
           [0022]      FIG. 3  is a schematic diagram of a system and method for verifying that the aircraft&#39;s communication link is operational. 
           [0023]      FIG. 4  is an overall process flow diagram for operation of the aircraft&#39;s auxiliary power unit. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]      FIG. 1  is a flowchart of one implementation of a method for increasing the fuel efficiency of an aircraft. In step  110 , at least one operating parameter of one of the aircraft&#39;s subsystems is measured during flight. Typically, the measured parameter is one of a set of parameters that are regularly transmitted from the aircraft to a ground station in routine communications. Optionally, it would be possible to obtain the operating parameter in other ways, such as by direct measurement on the aircraft. 
         [0025]    In step  120 , the parameter is evaluated to determine if it meets predetermined requirements. For example, the parameter may be a numerical value that is compared against a predetermined threshold. 
         [0026]    If the parameter does not meet the predetermined requirements, then the status of the subsystem, e.g., the APUOD status and/or the aircraft is changed (step  130 ), typically by updating the system of aircraft and subsystem information (step  140 ), for instance by updating one or more databases. According to some implementations, the evaluation done on a current flight is effective for changing the status of the aircraft on a next or future flight. 
         [0027]    In step  150 , a communication is sent to one or more recipients. The content of the communication may include the operating parameter compared to one or more predetermined thresholds, an indication of the operating parameter requirement and/or an indication of the change in status for the aircraft and/or subsystem. 
         [0028]    In step  160 , if the operating parameter meets the predetermined requirements, the next flight is operated with no changes to the status of the aircraft and/or subsystem (i.e., no changes based on the operating parameter). In step  170 , the system is updated accordingly, reflecting that the reliability testing has been completed and passed. In step  180 , a communication of the relevant test information and status is sent to one or more recipients. 
         [0029]      FIG. 2  is a flowchart showing a second implementation of a method for increasing the operating efficiency and safety of an aircraft. In step  210 , a communication of routine in-flight data is received. In step  220 , the condition or “health” of the APU is evaluated. Specifically, the condition of the APU can be correlated to its exhaust gas temperature taken at one or more times, one or more locations and/or subject to correcting factors. The systems and methods described herein extract one or more APU exhaust gas temperature values from the routine in-flight data. 
         [0030]    In specific implementations, a “corrected average exhaust gas temperature” (Avg EGT) value is used. For example, the CT5ATP value can be used. Of course, it would be possible to use other values, such as other averages based on a different number of records or readings. For convenience as used herein, the term Avg EGT is defined to include a single temperature or an average of multiple temperatures (including the CT5ATP value), and also includes correcting factors. 
         [0031]    If it is determined that the Avg EGT value is below a Watchlist Value (e.g., 593° C.) (step  230 ), the system is updated and the status of the APU and aircraft are unchanged (APUOD) (step  240 ). 
         [0032]    If the Avg EGT value is at or above 593° C. and below a Lower Limit Value (e.g., 604° C.) (step  250 ), then the system is updated to reflect that the aircraft has been added to a watch list (step  252 ) and the APUOD status is unchanged. In step  254 , one or more communications are sent, such as a communication to a Powerplant Engineer regarding the watch-listed status of the aircraft. Such communications can be sent by e-mail, text message, telephone, IT dashboard and/or other suitable formats. By adding the aircraft to the watch list, relevant personnel are reminded to pay it special attention with the possibility to take maintenance action with the goal of seeing that it is not required to be changed to APUCR. 
         [0033]    In step  256 , it is determined whether the APU Avg EGT value is at or above 604° C. and below an Upper Limit value (e.g., 632° C.). If so, then the system is updated (step  258 ) to reflect that the APU must be run continuously (APUCR) on ETOPS flights. In step  260 , one or more communications are sent to recipients. For example, communications can be sent to an authority that controls and schedules aircraft maintenance and an authority that dispatches aircraft prior to flight. 
         [0034]    In step  262 , it is determined whether the APU Avg EGT value is at or above the Upper Limit Value (e.g., 632° C.). If so, the system is updated in step  264  to reflect that the aircraft does not qualify for ETOPS operation. In step  266 , one or more communications are transmitted to various entities such as maintenance control, dispatch control and others to reflect the aircraft&#39;s change in status. 
         [0035]    In step  268 , it is determined whether the APU Avg EGT value was unreported in the routine in-flight data. If so, the system is updated in step  270  to reflect that no data was received, and one or more communications are sent in step  272 . 
         [0036]    In step  274 , it is determined whether the APU failed to start within the OEM specifications (currently  3  start attempts). If so, an optional subtest  276  determines whether the APU runs normally while the aircraft is on the ground. If so, then the system is updated to reflect that the APU must be run continuously (APUCR) (step  278 ). In step  280 , one or more communications are sent. 
         [0037]    In step  282 , it is determined whether the APU failed to start with the fault light illuminated. If so, an optional subtest  276  determines whether the APU runs normally while the aircraft is on the ground. If so, then the system is updated to reflect that the APU must be APUCR (step  278 ). In step  280 , one or more communications are sent. In step  280 , one or more communications are sent. 
         [0038]    In step  276 , it is determined if the APU does not start successfully on the ground. If it does not, the system is updated to reflect that the aircraft is no longer qualified for ETOPS (step  284 ). 
         [0039]    In step  286 , it is determined that the APU has successfully passed a cold soak start test. Accordingly, the system is updated to reflect the status of the APU and aircraft remain APUOD, i.e., the APU need only be operated on demand. 
         [0040]    In  FIG. 3 , one implementation of a system and method for verifying operation of the communication link by which data about an aircraft subsystem (e.g., the Avg EGT of the APU) is operational. In step  302 , it is assumed that there has been an information technology (IT) outage. One such outage that would be monitored is whether the airline&#39;s link to the routine in-flight data communication from the aircraft to a ground station is properly receiving all communications. 
         [0041]    In step  310 , assuming there is an outage; the airline&#39;s relevant departments are alerted. In step  320 , these departments begin troubleshooting the outage. In step  330 , it is determined whether two hours have elapsed. If so, and if the outage has been restored, then operation continues normally (step  340 ). 
         [0042]    If not, however, then IT confirms the outage (step  350 ), and maintenance control is notified (step  360 ) and the monitoring of the situation continues. In addition, after an outage of at least three hours, the system is updated and communications are sent. Specifically, if a data outage cannot be resolved within a predetermined timeframe, then the status of all affected aircraft is changed to require that the APU be APUCR. This is a conservative course of action to address the possibility that an aircraft may be required to change to APUCR for any parameters that dictate a status change as stated above due to loss of communication. 
         [0043]      FIG. 4  is an overall process flow diagram for the APUOD systems  400  and methods. As indicated at the left hand side of the figure, the Aircraft Condition Monitoring System (ACMS)/Aircraft Communication Addressing and Reporting System (ACARS) system  402  reports in-flight or on ground APU actions, APU health data (including the APU Avg EGT values and information on APU starts) and pilot reports of cold soak start testing for an aircraft. 
         [0044]    This information may be received by an entity other than the airline operating the aircraft, such as is represented by the AIRINC server bank  404  in  FIG. 4 . Subsequently, this information flows to the airline&#39;s computer systems, such as through one or more servers identified in  FIG. 4  as the airline&#39;s Flight Operations IT servers  406 . As described, the airline&#39;s computer systems are programmed with specific instructions to receive the information, evaluate the information, cue actions to be taken, update the status of the aircraft and send communications. 
         [0045]    Specifically, the APU health data is used in processes implemented on the IT servers  406 , the Ground Monitoring server  408  and the TIBCO servers  410 . For example, a controller is programmed to compare the Avg EGT data to predetermined requirements. If the APU Avg EGT value is at or above 593° C., then the aircraft is watch-listed in the system, and one or more communications are sent to a Powerplant Engineering (PPE) function  412 . This function can then monitor the performance of the aircraft even more closely. The status of the aircraft remains unchanged. 
         [0046]    If the Avg EGT value of the APU is at or above 604° C. and below 632° C., then an urgent communication is sent to a Maintenance Control (MX Control) function  414  and the PPE function  412 . The status of the aircraft is updated to APUCR to indicate that the aircraft&#39;s APU must be operated continuously until it undergoes another status change. 
         [0047]    Communications can be sent via IT dashboards, pop-up screens, text messaging, telephone, and other communication links, such as other broadcast communication techniques, where appropriate. Some communications are directed to one or more individual recipients, whereas other classes of communications are broadcast to all members of a particular class (e.g., all MX Control screens). 
         [0048]    The Ground Monitoring function includes software implemented to function as a reliability health monitor to ensure that data from the aircraft is properly received through the servers at regular intervals. This provides confidence that the computer systems are functioning properly. 
         [0049]    The dispatch function uses dispatch release software to generate ETOPS flight plans. The Dispatcher determines through communication the status of the aircraft (APUOD or APUCR) and inputs the status to the Flight Planning Worksheet software. This software automatically determines fuel load depending on whether the APU will be operated APUOD or APUCR. The Flight Plan will be generated automatically with clear designation as to the status of the aircraft for Flight Crew verification. 
         [0050]    The system automatically tracks the completion of successful cold soak start testing whether accomplished based upon a required repetitive interval or post-maintenance requirements. The system takes into account whether: the aircraft is scheduled on a qualifying flight segment ensuring adequate cold soak start test requirements, the segment is ETOPS or non-ETOPS, the aircraft has adequate turn time, and the flight terminates at a maintenance facility. If the aircraft status has been changed to APUCR, the system prohibits a cold soak start test on an ETOPS flight segment and a notification will not be sent to the Flight Crew to conduct the test. 
         [0051]    One implementation includes the ACARS report screen selection for the Flight Crew to select and transmit results of cold soak start tests. The Flight Crew includes the number and altitude of APU start attempts conducted. Another implementation is an enhanced APU health report not requiring Flight Crew reporting. The system will also retrieve APU rotor speed of greater than 90% to determine successful shutdown versus auto-shutdown and the altitude at which the start attempts were conducted. Once the data is retrieved that the cold soak start test was conducted, the system will validate that the APU start was conducted within cold soak start test parameters. If the cold soak start test is successful, a communication is sent out to MX Control and the APUOD eligibility is also renewed. If the cold soak start testing was found to be invalid, the system converts the data to an APU start and the APUOD eligibility will not be renewed. In the case of either a valid or invalid cold soak start test failing, MX Control will be notified through an electronic communication. 
         [0052]    The possible embodiments include those implementations where the system monitors the condition, or “health” of the APU as correlated to any of the APU operating performance indicators. The possible embodiments include those implementations for use on those aircraft without electrical back-up requiring an APU, as well as aircraft with electrical back-up where the APU is not required for ETOPS operations. 
         [0053]    The described process makes use of a three-level tiered response (i.e., akin to a green light, yellow light, red light approach), but it would of course be possible to implement the system using two levels or four levels. Indeed, in other implementations, instead of the described single intermediate level for watch-listed status, there may be multiple intermediate levels. Any specific numerical values detailed above, including temperature levels, can be dynamic and may be changed to meet program requirements, and should not be taken as limiting in scope. 
         [0054]    In view of the many possible embodiments to which the disclosed principles may be applied, it should be recognized that the illustrated embodiments are only preferred examples and should not be taken as limiting in scope. Rather, the scope of protection is defined by the following claims. We therefore claim all that comes within the scope and spirit of these claims.