DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Response to Amendment
This Office action is responsive to the amendment filed 23 February 2026. Claims 1-20 are pending and are examined.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-12 and 14-20 are rejected under 35 U.S.C. 103 as being unpatentable over Miller (2017/0159569) in view of Spadaccini (Deposit Formation and Mitigation in Aircraft Fuels).
Regarding claim 1, Miller teaches a method of operating a gas turbine engine (100, Fig.3), the gas turbine engine comprising: an engine core (Fig. 3) comprising a turbine (106, Fig. 3), a compressor (112, 114), a combustor (116) arranged to combust a fuel (¶32), and a core shaft (124, 126) connecting the turbine to the compressor (Fig. 3); a fan (104) located upstream of the engine core; a fan shaft (Fig. 3); a main gearbox (136) that receives an input from the core shaft and outputs drive to the fan via the fan shaft (¶26); a primary oil loop system (150) arranged to supply oil to lubricate the main gearbox (¶29); and a heat exchange system (200, Fig. 6) arranged to transfer heat between the oil and the fuel (¶33), the oil having an average temperature of at least 180 C on entry to the heat exchange system (¶39, 232 C-315 C at inlet, which is at least 180 C), wherein the method comprises controlling the heat exchange system so as to raise the fuel temperature to at least 135 C on entry to the combustor (¶39, fuel outlet temperature, 232 C-315 C, which is at least 135 C).
Miller doesn’t specify cruise conditions and an oxygen level in the fuel.
Miller teaches the jet engine is for an aircraft (Figs. 1 and 2 show the jet engine mounted to an aircraft.) The aircraft appears to be a passenger aircraft. When flying, aircrafts are designed to operate at cruise conditions for efficiency purposes.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the engine of Miller have operate at cruise conditions, in order to allow the airplane to operate efficiently in flight.
As discussed so far, Miller doesn’t teach an oxygen level in the fuel. Miller teaches a deoxygenation unit 212 that deoxygenates the fuel to reduce coke formation (¶32). Miller doesn’t teach a level to which the fuel is deoxygenates.
Spadaccini teaches that for coke formation to be avoided using jet fuel oxygen levels in the fuel need to be reduced from 70 ppm to less than 5 ppm (First paragraph, background). This teaches the oxygen level in the fuel needs to be reduced but not eliminated.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the engine of Miller have a fuel with oxygen levels of less than 5 ppm after deoxygenation, as taught by Spadaccini, in order to reduce coke formation. Thus, the fuel, comprising oxygen is provided to the combustor as claimed (e.g., fuel with 4 ppm Oxygen).
Regarding claim 2, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches transferring heat from the oil to the fuel in the heat exchange system so as to raise the fuel temperature to an average of at least 170 C on entry to the combustor at cruise conditions (¶39, fuel outlet temperature, 232 C-315 C, which is at least 170 C).
Regarding claim 3, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches transferring heat from the oil to the fuel in the heat exchange system so as to raise the fuel temperature to an average of at least 190 C on entry to the combustor at cruise conditions (¶39, fuel outlet temperature, 232 C-315 C, which is at least 190 C).
Regarding claim 4, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches transferring heat from the oil to the fuel in the heat exchange system so as to raise the fuel temperature to an average of at least 200 C on entry to the combustor at cruise conditions (¶39, fuel outlet temperature, 232 C-315 C, which is at least 200 C).
Regarding claim 5, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches an integrated drive generator (252, Fig. 6); and a secondary oil loop system (204) arranged to provide oil to the integrated drive generator (Fig. 6); wherein the heat exchange system comprises an oil-oil heat exchanger (262) arranged to transfer heat between the oil of the primary loop system and the oil of the secondary loop system (¶49).
Regarding claim 6, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches two branches through which oil flows (Fig. 6, a first branch through oil-oil heat exchanger 262 and a second branch that bypasses 262), to provide a parallel heat exchanger configuration.
In Fig. 6, Miller doesn’t teach an air-oil heat exchanger on the primary oil loop.
In Fig. 5, Miller teaches an air-oil heat exchanger 256 on the primary loop. In ¶45, ¶46, Miller teaches the air-oil heat exchanger can be located upstream or downstream of the fuel-oil heat exchangers and the system can include additional heat exchangers. The air-oil heat exchanger provides additional cooling capacity to remove heat from oil prior to it entering the engine.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the heat exchange system of Fig. 6 of Miller have a an air-oil heat exchanger, and wherein the oil-oil heat exchanger is on the same branch as the air-oil heat exchanger, as taught by Fig. 5 of Miller, in order to provide additional cooling capacity for the oil in the engine.
Regarding claim 7, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches an integrated drive generator (252, Fig. 6); and a secondary oil loop system (204) arranged to provide oil to the integrated drive generator; and the heat exchange system comprises: a primary fuel-oil heat exchanger (218) arranged to receive the fuel and oil from the primary oil loop system (Fig. 6); and a secondary fuel-oil heat exchanger (220) arranged to receive the fuel and oil from the secondary oil loop system (Fig. 6); and wherein the method comprises transferring heat between the oil from the secondary oil loop system and the fuel using the secondary fuel-oil heat exchanger (¶33).
Regarding claim 8, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the fuel flows through the secondary fuel-oil heat exchanger prior to flowing through the primary fuel-oil heat exchanger, such that heat is transferred from the oil in the secondary oil loop system to the fuel before heat is transferred from the oil in the primary oil loop system to the fuel (Fig. 6, the secondary fuel-oil heat exchanger 220 is upstream of the primary fuel-oil heat exchanger 218).
Regarding claim 9, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the controlling the heat exchange system so as to raise the fuel temperature comprises adjusting an amount of fuel sent through at least one of the primary fuel-oil heat exchanger and the secondary fuel-oil heat exchanger (Fig. 6, ¶34, bypass lines 234 and 238 and bypass valves 236 and 240 allow the amount of fuel sent through at least one of the primary fuel-oil heat exchangers and secondary fuel-oil heat exchanger to be adjusted).
Regarding claim 10, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the heat exchange system comprises at least one bypass pipe (234, 238) arranged to allow fuel to bypass a heat exchanger of the heat exchange system (Fig. 6), and wherein the method comprises adjusting the amount of fuel sent through the bypass pipe instead of through the heat exchanger (¶34, Miller teaches bypassing the heat exchanger using controllable valves).
Miller doesn’t explicitly teach the bypass is based on the fuel temperature. The point of the bypass is to avoid further heating of the fuel in the heat exchanger. Miller teaches maintaining the fuel temperature below a temperature limit (¶005).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the heat exchange system of Miller operate to adjust the amount of fuel sent through the bypass pipe instead of through the heat exchanger based on fuel temperature, as suggested by Miller, in order to keep the fuel temperature below the fuel temperature limits.
Regarding claim 11, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches more heat is output into oil in the primary closed loop system by the main gearbox than is output into oil in the secondary closed loop system by the integrated drive generator (¶50, when the VFG doesn’t generate a lot of heat, the excess heat transfer capacity is used for the main engine components like the main gearbox).
Regarding claim 12, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the heat exchange system comprises multiple heat exchangers arranged to cool the oil, the multiple heat exchangers including a fuel-oil heat exchanger (218, 220) and at least one of: (i) an air-oil heat exchanger; and (ii) an oil-oil heat exchanger 262, having a flow of oil from a different source flowing therethrough (Fig. 6).
Regarding claim 14, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the primary closed loop system and the secondary closed loop system are configured to interact via at least one oil-oil heat exchanger such that heat may be transferred from one flow of oil to the other (Fig. 6, ¶50).
Regarding claim 15, Miller teaches a gas turbine engine (100, Fig.3) for an aircraft (Figs. 1 and 2), the gas turbine engine comprising: an engine core (Fig. 3) comprising a turbine (106, Fig. 3), a compressor (112, 114), a combustor (116) arranged to combust a fuel (¶32), and a core shaft (124, 126) connecting the turbine to the compressor (Fig. 3); a fan (104) located upstream of the engine core (Fig. 3); a fan shaft (Fig. 3); a main gearbox (136) arranged to receive an input from the core shaft and to output drive to the fan via the fan shaft (¶26); a primary oil loop system (150, Fig. 6) arranged to supply oil to lubricate the main gearbox; and a heat exchange system (200, Fig. 6) arranged to transfer heat between the oil and the fuel (¶33), the primary oil loop system being arranged such that the oil has an average temperature of at least 180 C on entry to the heat exchange system (¶39, 232 C-315 C at inlet, which is at least 180 C), and wherein the heat exchange system is arranged to raise the fuel temperature to an average of at least 135 C on entry to the combustor (¶39, fuel outlet temperature, 232 C-315 C, which is at least 135 C).
Miller doesn’t specify cruise conditions and an oxygen level in the fuel.
Miller teaches the jet engine is for an aircraft (Figs. 1 and 2 show the jet engine mounted to an aircraft.) The aircraft appears to be a passenger aircraft. When flying, aircrafts are designed to operate at cruise conditions for efficiency purposes.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the engine of Miller have operate at cruise conditions, in order to allow the airplane to operate efficiently in flight.
As discussed so far, Miller doesn’t teach an oxygen level in the fuel. Miller teaches a deoxygenation unit 212 that deoxygenates the fuel to reduce coke formation (¶32). Miller doesn’t teach a level to which the fuel is deoxygenates.
Spadaccini teaches that for coke formation to be avoided using jet fuel oxygen levels in the fuel need to be reduced from 70 ppm to less than 5 ppm (First paragraph, background). This teaches the oxygen level in the fuel needs to be reduced but not eliminated.
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the engine of Miller have a fuel with oxygen levels of less than 5 ppm after deoxygenation, as taught by Spadaccini, in order to reduce coke formation. Thus, the fuel, comprising oxygen is provided to the combustor as claimed (e.g., fuel with 4 ppm Oxygen).
Regarding claim 16, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the gas turbine engine further comprises an auxiliary gearbox, and wherein the oil in the primary oil loop system is arranged to cool the auxiliary gearbox, thereby increasing in temperature (¶29, engine has various gears including power gearbox and accessory gearbox that are cooled by the lubrication system).
Regarding claim 17, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches transferring heat from the oil to the fuel in the heat exchange system so as to raise the fuel temperature to an average of at least 190 C on entry to the combustor at cruise conditions (¶39, fuel outlet temperature, 232 C-315 C, which is at least 190 C).
Regarding claim 18, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches an integrated drive generator (252, Fig. 6), and a secondary closed loop oil system (204), wherein the secondary closed loop system is arranged to provide oil to the integrated drive generator, and wherein the heat exchange system is arranged to transfer heat from the oil in the secondary closed loop system to the fuel (Fig. 6).
Regarding claim 19, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the heat exchange system comprises multiple heat exchangers arranged to cool the oil, the multiple heat exchangers including a fuel-oil heat exchanger (218, 220) and at least one of: (i) an air-oil heat exchanger; and (ii) an oil-oil heat exchanger 262, having a flow of oil from a different source flowing therethrough (Fig. 6).
Regarding claim 20, Miller in view of Spadaccini teaches the invention discussed above and Miller further teaches the primary closed loop system 204 and the secondary closed loop system 202 are configured to interact via at least one oil-oil heat exchanger 262 such that heat may be transferred from one flow of oil to the other (Fig. 6).
Claim 13 is rejected under 35 U.S.C. 103 as being unpatentable over Miller (2017/0159569) in view of Spadaccini as applied to claim 1 above, and further in view of Bosak (US 2021/0172375).
Regarding claim 13, Miller in view of Spadaccini teaches the invention as discussed above for claim 1 and Miller further teaches the heat exchange system comprises multiple heat exchangers arranged to cool the oil, and wherein the multiple heat exchangers include a fuel-oil heat exchanger and at least one other heat exchanger (Fig. 6).
Miller in view of Spadaccini doesn’t teach the heat exchangers are arranged in a parallel configuration and the method comprises sending a proportion of the oil through each branch of the parallel configuration, and adjusting that proportion to vary how much oil flows through the fuel-oil heat exchanger and how much oil flows through a heat exchanger on the other branch.
Bosak teaches a heat exchange system for a gas turbine engine of an aircraft (¶10, Fig. 1). The heat exchangers include a fuel-oil heat exchanger (22) and an air-oil heat exchanger (24) arranged in a parallel configuration. A pump (14, 16) is provided to each of the heat exchangers that allow proportion of oil flowing through each heat exchanger to be adjusted (¶34-¶37). The control allows the SFC to be maximized or the average oil temperature to be controlled during different flight points (¶38).
It would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to make the engine of Miller in view of Spadaccini have the heat exchangers arranged in a parallel configuration and the method comprises sending a proportion of the oil through each branch of the parallel configuration, and adjusting that proportion to vary how much oil flows through the fuel-oil heat exchanger and how much oil flows through a heat exchanger on the other branch, as taught by Bosak, in order to maximize the SFC and control the oil temperature during the various points of the flight envelope.
Applicant’s arguments with respect to the pending claims have been carefully considered
but are moot because the arguments do not apply to the new grounds of rejection discussed above that were necessitated by Applicant’s amendments. However, to the extent possible Applicant arguments have been addressed in the body of the rejections above, at the appropriate locations.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to DAVID OLYNICK whose telephone number is (571)272-2355. The examiner can normally be reached M-F: 7:30 am-5 pm (ET).
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If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Phuttiwat Wongwian can be reached at (571) 270-5426. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300.
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/DAVID P. OLYNICK/Primary Examiner, Art Unit 3741
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