# US 11,306,654 B2 · Gas turbine engine system wear reduction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,306,654 B2 - Document ID: US11306654B2 - Status: Granted - Kind: B2 - Application number: 16/695,290 - Filed: 2019-11-26 - Published: 2020-06-25 - Granted: 2022-04-19 - Earliest claimed: 2018-12-19 - Assignees: Raytheon Technologies Corporation - Applicants: United Technologies Corporation - Inventors: Stephen A. Witalis; Ramesh Rajagopalan; Subhradeep Chowdhury - Web page: https://patentgrep.com/patent/US11306654B2 ## CPC - F02C 6/08: the gas being bled from the gas-turbine compressor - F02C 9/26: Control of fuel supply (F02C9/48 takes precedence; fuel valves F02C7/232) - F02C 9/42: specially adapted for the control of two or more plants simultaneously - F02C 9/52: by bleeding or by-passing the working fluid - F02C 9/28: Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed (F02C9/30 - F02C9/38, F02C9/44 take precedence) - F05D 2260/85: Starting - F05D 2260/96: Preventing, counteracting or reducing vibration or noise - F05D 2270/071: in particular at idling speed - 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 An engine system for an aircraft includes a first gas turbine engine, a second gas turbine engine, and a control system. The control system is configured to operate the first gas turbine engine with an idle fuel burn schedule in a taxi mode of the aircraft and operate the second gas turbine engine with a sub-idle fuel burn schedule in the taxi mode of the aircraft. The sub-idle fuel burn schedule includes a reduction of the idle fuel burn schedule. A fuel flow of the first gas turbine engine and the second gas turbine engine is increased above the idle fuel burn schedule prior to takeoff of the aircraft. ## Claims ### Claim 1 An engine system for an aircraft, the engine system comprising: a first gas turbine engine; a second gas turbine engine; a control system configured to: operate the first gas turbine engine with an idle fuel burn schedule in a taxi mode of the aircraft; operate the second gas turbine engine with a sub-idle fuel burn schedule in the taxi mode of the aircraft, the sub-idle fuel burn schedule comprising a reduction of the idle fuel burn schedule; and increase a fuel flow of the first gas turbine engine and the second gas turbine engine above the idle fuel burn schedule prior to takeoff of the aircraft. ### Claim 2 (depends on 1) The engine system of claim 1, wherein the control system is further configured to: transition the second gas turbine engine from the sub-idle fuel burn schedule to the idle fuel burn schedule in a prepare-for-takeoff mode prior to acceleration of the first gas turbine engine and the second gas turbine engine for takeoff of the aircraft. ### Claim 3 (depends on 1) The engine system of claim 1, wherein the control system is further configured to: operate the first gas turbine engine with the sub-idle fuel burn schedule based on detecting landing of the aircraft; and operate the second gas turbine engine with the idle fuel burn schedule based on detecting landing of the aircraft. ### Claim 4 (depends on 1) The engine system of claim 1, wherein the control system is further configured to alternate a designation of the first gas turbine engine and the second gas turbine engine between two or more gas turbine engines of the aircraft. ### Claim 5 (depends on 4) The engine system of claim 4, wherein the control system is further configured to track a sub-idle time of the two or more gas turbine engines and alternate the designation of the first gas turbine engine and the second gas turbine engine to substantially balance the sub-idle time of the two or more gas turbine engines for the aircraft. ### Claim 6 (depends on 1) The engine system of claim 1, wherein at least one engine bleed schedule is adjusted corresponding to the sub-idle fuel burn schedule to control a compressor work distribution during sub-idle operation. ### Claim 7 (depends on 6) The engine system of claim 6, wherein adjustment to the at least one engine bleed schedule increases an engine bleed flow to at least one environment control system of the aircraft during sub-idle operation. ### Claim 8 (depends on 1) The engine system of claim 1, wherein the control system comprises one or more of an engine controller and an aircraft controller. ### Claim 9 (depends on 1) The engine system of claim 1, wherein the first gas turbine engine comprises: a fan section; a compressor section operably coupled to the fan section; a combustor section; a turbine section operably coupled to the compressor section; and an engine controller configured to: meter a fuel flow to the combustor section according to the idle fuel burn schedule in a first taxi mode of the aircraft; and meter the fuel flow to the combustor section according to the sub-idle fuel burn schedule in a second taxi mode of the aircraft. ### Claim 10 (depends on 9) The engine system of claim 9, wherein the first taxi mode comprises a taxi-to-flight-line mode prior to takeoff of the aircraft and the second taxi mode comprises a taxi-to-gate mode after landing of the aircraft. ### Claim 11 (depends on 9) The engine system of claim 9, wherein the first taxi mode comprises a taxi-to-gate mode after landing of the aircraft and the second taxi mode comprises a taxi-to-flight-line mode prior to takeoff of the aircraft. ### Claim 12 (depends on 11) The engine system of claim 11, wherein the engine controller is further configured to transition from the sub-idle fuel burn schedule to the idle fuel burn schedule in a prepare-for-takeoff mode prior to acceleration for takeoff of the aircraft. ### Claim 13 (depends on 9) The engine system of claim 9, wherein the engine controller is further configured to adjust at least one engine bleed schedule of the compressor section corresponding to the sub-idle fuel burn schedule to control a compressor work distribution during sub-idle operation of the first gas turbine engine. ### Claim 14 A method of controlling an engine system of an aircraft, the method comprising: operating, by a control system, a first gas turbine engine of the engine system with an idle fuel burn schedule in a taxi mode of the aircraft; operating, by the control system, a second gas turbine engine of the engine system with a sub-idle fuel burn schedule in the taxi mode of the aircraft, the sub-idle fuel burn schedule comprising a reduction of the idle fuel burn schedule; and increasing, by the control system, a fuel flow of the first gas turbine engine and the second gas turbine engine above the idle fuel burn schedule prior to takeoff of the aircraft. ### Claim 15 (depends on 14) The method of claim 14, further comprising: transitioning the second gas turbine engine from the sub-idle fuel burn schedule to the idle fuel burn schedule in a prepare-for-takeoff mode prior to acceleration of the first gas turbine engine and the second gas turbine engine for takeoff of the aircraft. ### Claim 16 (depends on 14) The method of claim 14, further comprising: operating the first gas turbine engine with the sub-idle fuel burn schedule based on detecting landing of the aircraft; and operating the second gas turbine engine with the idle fuel burn schedule based on detecting landing of the aircraft. ### Claim 17 (depends on 14) The method of claim 14, further comprising: alternating a designation of the first gas turbine engine and the second gas turbine engine between two or more gas turbine engines of the aircraft. ### Claim 18 (depends on 17) The method of claim 17, further comprising: tracking a sub-idle time of the two or more gas turbine engines and alternate the designation of the first gas turbine engine and the second gas turbine engine to substantially balance the sub-idle time of the two or more gas turbine engines for the aircraft. ### Claim 19 (depends on 14) The method of claim 14, further comprising: adjusting at least one engine bleed schedule corresponding to the sub-idle fuel burn schedule to control a compressor work distribution during sub-idle operation. ### Claim 20 (depends on 19) The method of claim 19, wherein adjusting the at least one engine bleed schedule increases an engine bleed flow to at least one environment control system of the aircraft during sub-idle operation.