# US 9,437,054 B2 · Method for predicting an auxiliary power unit fault > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,437,054 B2 - Document ID: US9437054B2 - Status: Granted - Kind: B2 - Application number: 14/265,573 - Filed: 2014-04-30 - Published: 2015-04-09 - Granted: 2016-09-06 - Earliest claimed: 2013-10-07 - Assignees: GE Aviation Systems LLC - Applicants: GE Aviation Systems Limited - Inventors: Christopher Joseph Catt - Web page: https://patentgrep.com/patent/US9437054B2 ## CPC - G07C 5/0808: {Diagnosing performance data (testing of vehicles G01M17/00; testing of electrical installation on vehicles G01R31/005)} - B64D 41/00: Power installations for auxiliary purposes - F01D 17/02: Arrangement of sensing elements - F01D 17/20: Devices dealing with sensing elements or final actuators or transmitting means between them, e.g. power-assisted (sensing elements alone F01D17/02; final actuators alone F01D17/10) - F01D 21/003: {Arrangements for testing or measuring (for measuring vibrations G01H)} - F02C 9/00: Controlling gas-turbine plants; Controlling fuel supply in air- breathing jet-propulsion plants (controlling air intakes F02C7/057; controlling turbines F01D; controlling compressors F04D27/00; controlling in general G05) - G07C 5/008: {communicating information to a remotely located station (transmission systems for measured values G08C)} - B64D 2045/0085: {Devices for aircraft health monitoring, e.g. monitoring flutter or vibration} - F05D 2220/50: for auxiliary power units (APU's) - F05D 2260/80: Diagnostics - F05D 2270/3032: excessive temperatures, e.g. caused by overheating - F05D 2270/304: Spool rotational speed - F05D 2270/44: active, predictive, or anticipative - G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE - B64D: EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT - F01D: NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES (machines or engines for liquids F03; non-positive displacement pumps F04D) - F02C: GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS (construction of turbines F01D; jet-propulsion plants F02K; construction of compressors or fans F04; generating combustion products of high pressure or high velocity F23R; using gas turbines in compression refrigeration plants F25B11/00) - F05D: INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS ## Abstract A method of predicting an auxiliary power unit fault in an aircraft having an auxiliary power unit and multiple sensors related to the auxiliary power unit, components thereof, and systems related thereto, including receiving a sensor signal from at least one of the multiple sensors to define a sensor output, comparing the sensor output to a reference value and predicting a fault in the auxiliary power unit based on the comparison. ## Claims ### Claim 1 A method of predicting an auxiliary power unit fault in an aircraft having an auxiliary power unit and multiple sensors related to the auxiliary power unit, components thereof, and systems related thereto, the method comprising: receiving, during at least one of pre-flight or post-flight, a sensor signal from at least one of the multiple sensors to define a sensor output; comparing, by a controller, the sensor output to a reference value for the sensor output; predicting, by a controller, a fault associated with the auxiliary power unit based on the comparison and prior to an occurrence of the predicted fault; and providing, by a controller, an indication of the predicted fault. ### Claim 2 (depends on 1) The method of claim 1, further comprising: receiving at least one of an altitude signal, a speed signal, or performances parameters outputted by an engine. ### Claim 3 (depends on 1) The method of claim 1, further comprising: determining when the aircraft is in pre-flight or post-flight. ### Claim 4 (depends on 1) The method of claim 1, further comprising: receiving information identifying an exhaust gas temperature during the post-flight, wherein the predicting the fault includes predicting the fault based at least in part on the comparing indicating that the exhaust gas temperature is greater than a predetermined temperature. ### Claim 5 (depends on 1) The method of claim 1, wherein aggregating the sensor output over time to define aggregated sensor data, and the comparing includes comparing the aggregated sensor data to the reference value. ### Claim 6 (depends on 5) The method of claim 5, wherein the aggregating the sensor output over time comprises aggregating the sensor output over multiple flights. ### Claim 7 (depends on 5) The method of claim 5, wherein the aggregated sensor data comprises at least one of a median value, a running median value, or a historical median value. ### Claim 8 (depends on 1) The method of claim 1, further comprising: receiving information identifying a median inlet temperature during the pre-flight, wherein the predicting the fault includes predicting the fault based at least in part on the comparing indicating that the median inlet temperature was greater than 45 degrees Celsius. ### Claim 9 (depends on 1) The method of claim 1, wherein the reference value is calculated from historical sensor output. ### Claim 10 (depends on 1) The method of claim 1, further comprising: receiving information identifying a surge control valve position during the post-flight, wherein the predicting the fault includes predicting the fault based at least in part on the comparing indicating the surge control valve position was less than −0.5 degrees or greater than 0.5 degrees. ### Claim 11 (depends on 1) The method of claim 1, further comprising: determining, from the sensor output, a time taken for the auxiliary power unit to start, and comparing the determined time to the reference value. ### Claim 12 (depends on 11) The method of claim 11, wherein the predicting the fault includes predicting the fault based on the comparing indicating the time taken for the auxiliary power unit to start was greater than 50 seconds. ### Claim 13 (depends on 1) The method of claim 1, wherein providing the indication comprises providing the indication on a primary flight display (PFD) in a cockpit of the aircraft. ### Claim 14 (depends on 1) The method of claim 1, wherein the predicting the fault comprises predicting the fault based on multiple comparisons. ### Claim 15 A system comprising: one or more devices configured to: receive, during at least one of pre-flight or post-flight, a sensor signal from at least one of a set of sensors, associated with an auxiliary power unit of an aircraft, to define a sensor output; compare the sensor output to a reference value for the sensor output; predict a fault associated with the auxiliary power unit based on the comparison and prior to an occurrence of the predicted fault; and provide an indication of the predicted fault. ### Claim 16 (depends on 15) The system of claim 15, wherein the one or more devices are further configured to: aggregate the sensor output over time to define aggregated sensor data, and the one or more devices, when comparing the sensor output to the reference value, are configured to: compare the aggregated sensor data to the reference value. ### Claim 17 (depends on 16) The system of claim 16, wherein the one or more devices, when aggregating the sensor output over time, are configured to: aggregate the sensor output over multiple flights. ### Claim 18 A non-transitory computer-readable medium storing instructions, the instructions comprising: one or more which, when executed by a processor of a device, cause the processor to: receive, during at least one of pre-flight or post-flight, a sensor signal from at least one of multiple sensors, associated with an auxiliary power unit of an aircraft, to define a sensor output; compare the sensor output to a reference value for the sensor output; predict a fault associated with the auxiliary power unit based on the comparison and prior to an occurrence of the predicted fault; and provide an indication of the predicted fault. ### Claim 19 (depends on 18) The non-transitory computer-readable medium of claim 18, wherein the instructions further include: one or more instructions to aggregate the sensor output over time to define aggregated sensor data, and the one or more instructions to compare the sensor output to the reference value include: one or more instructions to compare the aggregated sensor data to the reference value. ### Claim 20 (depends on 19) The non-transitory computer-readable medium of claim 19, wherein the one or more instructions to aggregate the sensor output over time include: one or more instructions to aggregate the sensor output over multiple flights.