Prosecution Insights
Last updated: April 19, 2026
Application No. 18/463,774

TURBINE ENGINE INCLUDING A FUEL SYSTEM

Final Rejection §112
Filed
Sep 08, 2023
Examiner
LIU, JINGCHEN
Art Unit
3741
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
General Electric Company
OA Round
4 (Final)
59%
Grant Probability
Moderate
5-6
OA Rounds
2y 7m
To Grant
99%
With Interview

Examiner Intelligence

Grants 59% of resolved cases
59%
Career Allow Rate
51 granted / 87 resolved
-11.4% vs TC avg
Strong +62% interview lift
Without
With
+62.0%
Interview Lift
resolved cases with interview
Typical timeline
2y 7m
Avg Prosecution
33 currently pending
Career history
120
Total Applications
across all art units

Statute-Specific Performance

§101
0.5%
-39.5% vs TC avg
§103
48.1%
+8.1% vs TC avg
§102
14.1%
-25.9% vs TC avg
§112
36.2%
-3.8% vs TC avg
Black line = Tech Center average estimate • Based on career data from 87 resolved cases

Office Action

§112
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 . Claim Rejections - 35 USC § 112 The following is a quotation of the first paragraph of 35 U.S.C. 112(a): (a) IN GENERAL.—The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor or joint inventor of carrying out the invention. The following is a quotation of the first paragraph of pre-AIA 35 U.S.C. 112: The specification shall contain a written description of the invention, and of the manner and process of making and using it, in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention. Claims 1, 4-7, 9, 12-13, 25-26, and 29 are rejected under 35 U.S.C. 112(a) or 35 U.S.C. 112 (pre-AIA ), first paragraph, as failing to comply with the written description requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to reasonably convey to one skilled in the relevant art that the inventor or a joint inventor, or for applications subject to pre-AIA 35 U.S.C. 112, the inventor(s), at the time the application was filed, had possession of the claimed invention. Regarding claim 1 and its dependents, recitation “a heat transfer loop thermally coupling the condenser with the fuel heat exchanger in order to transfer the heat from the combustion gases to the fuel, the heat transfer loop including a heat transfer fluid flowing therethrough, the heat transfer fluid being a heat transfer medium that remains in a fluid state when transferring heat to the fuel at cryogenic temperatures in the fuel heat exchanger, …, the heat transfer loop fluidly connected to the fuel heat exchanger for the heat transfer fluid to transfer the heat received from the combustion gases to the fuel such that the heat transfer fluid is cooled by the fuel” contains new matter because: - the recitation “the heat transfer fluid being a heat transfer medium that remains in a fluid state when transferring heat to the fuel at cryogenic temperatures in the fuel heat exchanger” requires the heat transfer fluid to be remained in the fluid state when passing through the fuel heat exchanger; - according to [0056], the specification discloses that the heat transfer fluids may be helium, nitrogen, supercritical carbon dioxide, a silicon-based heat transfer fluid (e.g., Syltherm™ 800 or Syltherm™ XLT, each produced by Dow of Midland, Michigan, USA), or sulfur hexafluoride, and according to [0065] and Fig. 5A the temperature of the heat transfer fluid exiting the condenser 104 is less than 212 degrees Fahrenheit, wherein i) supercritical carbon dioxide is a supercritical fluid that is a special state between gaseous state and liquid state, i.e., supercritical carbon dioxide is not a liquid state medium required for claim 1; and ii) the rest of the disclosed heat transfer fluids have different physical properties that requires different working temperatures and/or pressures in order to be remained in the liquid state when subject to the cryogenic temperature of fuel while passing through the fuel heat exchanger, and the specification does not disclose any structure(s)/component(s)/control step(s) to maintain the rest of the heat transfer fluids to be in the liquid state when passing through the fuel heat exchanger as required in claim 1, specifically, a) the boiling point of helium under standard ambient pressure is about -450 degrees Fahrenheit that is lower than the temperature of the cryogenic hydrogen, about -423 degrees Fahrenheit, and thus helium under standard ambient pressure are not in the liquid state when subjects to the cryogenic hydrogen; b) the boiling point of nitrogen under standard ambient pressure is about -320 degrees Fahrenheit, and when exiting the condenser with a temperature less than 212 degrees Fahrenheit, the nitrogen is in the gaseous state, and para. [0065] merely discloses the secondary heat exchanger 240 in Fig. 5A cools the heat transfer fluid without any disclosure of cooling the heat transfer fluid to the liquid state or a specific temperature enabling the nitrogen to be changed to the liquid state; c) the freezing point of Syltherm™ 800 is about -76 degrees Fahrenheit that is higher than the temperature of the cryogenic hydrogen, about -423 degrees Fahrenheit, and thus Syltherm™ 800 would be frozen when subjects to the cryogenic hydrogen; d) the freezing point of Syltherm™ XLT is about -168 degrees Fahrenheit that is higher than the temperature of the cryogenic hydrogen, about -423 degrees Fahrenheit, and thus Syltherm™ XLT would be frozen when subjects to the cryogenic hydrogen; and e) the boiling point of sulfur hexafluoride under standard ambient pressure is about -83 degrees Fahrenheit, and when exiting the condenser with a temperature less than 212 degrees Fahrenheit, the sulfur hexafluoride is in the gaseous state, and the para. [0065] merely discloses the secondary heat exchanger 240 in Fig. 5A cools the heat transfer fluid without any disclosure of cooling the heat transfer fluid to the liquid state or a specific temperature enabling the sulfur hexafluoride to be changed to the liquid state; - therefore, claim 1 and its dependent are rejected as new matter. Regarding claim 25, recitation “wherein the heat transfer fluid is one of helium, nitrogen, supercritical carbon dioxide, a silicon-based heat transfer fluid, or sulfur hexafluoride” contains new matter because a) supercritical carbon dioxide is a supercritical state medium that is not compatible with the claimed heat transfer fluid, which is required to be remained in the liquid state, as claimed in claim 1; and b) the specification does not disclose any structure(s)/component(s)/control step(s) to maintain helium, nitrogen, a silicon-based heat transfer fluid, or sulfur hexafluoride to be in the liquid state when passing through the fuel heat exchanger as required in claim 1, see explanation in the 112a rejection for claim 1 above. Regarding claim 29, I. recitation “wherein the secondary heat exchanger is a fluid-based heat exchanger comprising a fluid flow path through which a cooling fluid or a heating fluid from the separate engine system flows to exchange heat with the heat transfer fluid flowing through the heat transfer loop” contains new matter because: i) claim 1 defines that the secondary heat exchanger fluidly connected downstream of the condenser and upstream of the fuel heat exchanger in order for the heat transfer fluid to transfer heat to the separate engine system while passing through the secondary heat exchanger, i.e., the secondary heat exchanger receives the heat transfer fluid as a heating fluid; ii) the recitation “wherein the secondary heat exchanger is a fluid-based heat exchanger comprising a fluid flow path through which a cooling fluid or a heating fluid from the separate engine system flows to exchange heat with the heat transfer fluid flowing through the heat transfer loop” contains limitation that requires the secondary heat exchanger to receive the heat transfer fluid as a heating fluid and an additional heat fluid (the claimed heating fluid) from the separate engine system; iii) according to [0065], the specification only discloses the secondary heat exchanger 240 in Fig. 5A either transfers heat from the heat transfer fluid to the separate engine system or absorbs heat via the heat transfer fluid from the separate engine system, i.e., the disclosed secondary heat exchanger receives only one cooling fluid from the separate engine system and only one heating fluid that is the heat transfer fluid in order to transfer heat to the separate engine system; iv) therefore, the specification does not support the limitation of claim 29 that requires the claimed secondary heat exchanger to receive two heating fluid, and thus, claim 29 is rejected as new matter; and II. recitation “wherein the secondary heat exchanger is a fluid-based heat exchanger comprising a fluid flow path through which a cooling fluid from the separate engine system flows to exchange heat with the heat transfer fluid flowing through the heat transfer loop” contains new matter because: i) claim 1 defines that the secondary heat exchanger fluidly connected downstream of the condenser and upstream of the fuel heat exchanger in order for the heat transfer fluid to transfer heat to the separate engine system while passing through the secondary heat exchanger, and the heat transfer fluid being a heat transfer medium that remains in a fluid state when transferring heat to the fuel at cryogenic temperatures in the fuel heat exchanger, i.e., when entering the fuel heat exchanger, the heat transfer fluid is in the liquid state; ii) recitation “the secondary heat exchanger is a fluid-based heat exchanger comprising a fluid flow path through which a cooling fluid from the separate engine system flows to exchange heat with the heat transfer fluid flowing through the heat transfer loop” requires the secondary heat exchanger is a liquid-based heat exchanger to receive the heat transfer fluid and a cooling fluid from the separate engine system, i.e., at the secondary heat exchanger, the heat transfer fluid is in/changes to the liquid state, or the cooling fluid from the separate engine system is in the liquid state, or both of the heat transfer fluid is in/changes to the liquid state and the cooling fluid from the separate engine system is in the liquid state; iii) according to [0065] and Fig. 5A, the specification does not disclose any structure(s)/component(s)/control step(s) for the heat transfer fluid being/changing to the liquid state at the secondary heat changer and only discloses when the secondary heat exchanger is configured to absorb heat from the separate engine system, the fluid that receives by the secondary heat exchanger from the separate engine is a liquid state fluid (oil per [0065]) being used as a heating fluid in the secondary heat exchanger, which is conflicting with the claimed “cooling fluid” of claim 29; iv) therefore, the specification does not support the limitation of claim 29 that requires the claimed secondary heat exchanger to be a liquid-bases heat exchanger that receives a cooling fluid to absorb heat from the heat transfer fluid as required for claim 1, and thus, claim 29 is rejected as new matter; The following is a quotation of 35 U.S.C. 112(b): (b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention. The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph: The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention. Claims 25 and 29 are rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention. Regarding claim 25, recitation “wherein the heat transfer fluid is one of helium, nitrogen, supercritical carbon dioxide, a silicon-based heat transfer fluid, or sulfur hexafluoride” is unclear which medium(s) of the listed mediums is required for claim 25 because some of the listed mediums are not compatible with the heat transfer fluids required in claim 1, e.g., a) helium is in the gaseous state when subjects to the cryogenic temperature while passing through the fuel heat exchanger as explained in 112a rejection for claim 1 above; and b) supercritical carbon dioxide is a supercritical state of medium that is not a liquid state medium. Regarding claim 29, recitation “wherein the secondary heat exchanger is a fluid-based heat exchanger comprising a fluid flow path through which a cooling fluid or a heating fluid from the separate engine system flows to exchange heat with the heat transfer fluid flowing through the heat transfer loop” is indefinite because: i) it is unclear whether term “a fluid-based heat exchanger” means a) the secondary heat exchanger is a liquid-based heat exchanger (raises 112a issue, see rejection above); or b) the secondary heat exchanger receives fluid(s), and said fluid(s) may be in liquid state or gaseous state; ii) according to [0065], the specification only discloses the secondary heat exchanger either transfers heat from the heat transfer fluid to the separate engine system or absorbs heat from the separate engine system via the heat transfer fluid, and claim 1 requires the secondary heat exchanger transfer heat from the heat transfer fluid to the separate engine system, i.e., the fluid provided by the separate engine system needs to be a cooling fluid received by the secondary heat exchanger in order for the secondary heat exchanger to transfer heat to the separate engine system, and thus, it is unclear whether “a cooling fluid” is required for claim 29 (if fluid-based means liquid-based, raises 112a issue, see rejection above) or “a heating fluid is required for claim 29” (raises 112a issue, see rejection above), and it is further unclear that terms “cooling” and “heating” are respectively refers to/relative to which system, e.g., the cooling fluid at the secondary heat exchanger (absorb heat from the heat transfer fluid) may be a heating fluid in the separate engine system (heating a component in the separate engine system). The following is a quotation of 35 U.S.C. 112(d): (d) REFERENCE IN DEPENDENT FORMS.—Subject to subsection (e), a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers. The following is a quotation of pre-AIA 35 U.S.C. 112, fourth paragraph: Subject to the following paragraph [i.e., the fifth paragraph of pre-AIA 35 U.S.C. 112], a claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers. Claim 25 is rejected under 35 U.S.C. 112(d) or pre-AIA 35 U.S.C. 112, 4th paragraph, as being of improper dependent form for failing to further limit the subject matter of the claim upon which it depends, or for failing to include all the limitations of the claim upon which it depends because claim 25 contains limitation that is not compatible with the claimed heat transfer fluid in claim 1, e.g., a) helium is in the gaseous state when subjects to the cryogenic temperature while passing through the fuel heat exchanger as explained in the 112a rejection for claim 1 above; and b) supercritical carbon dioxide is a supercritical state of medium that is not a liquid state medium, and thus, claim 25 fails to include all the limitations of claim 1 upon which it depends. Applicant may cancel the claim(s), amend the claim(s) to place the claim(s) in proper dependent form, rewrite the claim(s) in independent form, or present a sufficient showing that the dependent claim(s) complies with the statutory requirements. Potential Allowable Subject Matter The references listed below have been further considered by the Examiner. Terwilliger 12215622 teaches a turbine engine for an aircraft, the turbine engine comprising: a fuel delivery assembly for fuel to flow therethrough; a core turbine engine including: a core air flow path for core air to flow therethrough; a condenser located downstream of the turbine to receive and cool the combustion gases to condense water from the combustion gases; a fuel heat exchanger thermally coupled to the condenser to receive heat from the combustion gases, the fuel heat exchanger located in the fuel delivery assembly to receive the fuel at cryogenic temperatures and heat the fuel by transferring the heat received from the combustion gases to the fuel; a heat transfer loop thermally coupling the condenser with the fuel heat exchanger in order to transfer the heat from the combustion gases to the fuel, the heat transfer loop including a heat transfer fluid flowing therethrough, the heat transfer fluid being a heat transfer medium that remains in a fluid state when transferring heat to the fuel at cryogenic temperatures in the fuel heat exchanger, the heat transfer loop fluidly connected to the condenser, the condenser having a fluid flow path for the heat transfer fluid to flow through the condenser and receive the heat from the combustion gases, the heat transfer loop fluidly connected to the fuel heat exchanger for the heat transfer fluid to transfer the heat received from the combustion gases to the fuel such that the heat transfer fluid is cooled by the fuel. JOUAN 20230243308 teaches a turbine engine : a fuel delivery assembly for fuel to flow therethrough; a core turbine engine including: a core air flow path for core air to flow therethrough; a exhaust-fluid heat exchanger receiving and cooling the combustion gases; a fuel heat exchanger thermally coupled to the exhaust-fluid heat exchanger to receive heat from the combustion gases, the fuel heat exchanger located in the fuel delivery assembly to receive the fuel at cryogenic temperatures and heat the fuel by transferring the heat received from the combustion gases to the fuel; a heat transfer loop thermally coupling the exhaust-fluid heat exchanger with the fuel heat exchanger in order to transfer the heat from the combustion gases to the fuel, the heat transfer loop including a heat transfer fluid flowing therethrough, the heat transfer fluid being a heat transfer medium that remains in a fluid state when transferring heat to the fuel at cryogenic temperatures in the fuel heat exchanger, the heat transfer loop fluidly connected to the exhaust-fluid heat exchanger, the exhaust-fluid heat exchanger having a fluid flow path for the heat transfer fluid to flow through the exhaust-fluid heat exchanger and receive the heat from the combustion gases, the heat transfer loop fluidly connected to the fuel heat exchanger for the heat transfer fluid to transfer the heat received from the combustion gases to the fuel such that the heat transfer fluid is cooled by the fuel. Brooks 20100192890 teaches a turbine engine for an aircraft, the turbine engine comprising: a fuel delivery assembly for fuel to flow therethrough; an engine-coolant-fluid heat exchanger configured to cool an engine coolant and transfer heat to a heat transfer fluid; a fuel heat exchanger thermally coupled to the engine-coolant-fluid heat exchanger to receive heat from the engine coolant, the fuel heat exchanger located in the fuel delivery assembly to receive the fuel at cryogenic temperatures and heat the fuel by transferring the heat received from the engine coolant to the fuel; a heat transfer loop thermally coupling the engine-coolant-fluid heat exchanger with the fuel heat exchanger in order to transfer the heat from the engine coolant to the fuel, the heat transfer loop including the heat transfer fluid flowing therethrough, the heat transfer loop fluidly connected to the engine-coolant-fluid heat exchanger, the engine-coolant-fluid heat exchanger having a fluid flow path for the heat transfer fluid to flow through the engine-coolant-fluid heat exchanger and receive the heat from the engine coolant, the heat transfer loop fluidly connected to the fuel heat exchanger for the heat transfer fluid to transfer the heat received from the engine coolant to the fuel such that the heat transfer fluid is cooled by the fuel; and a secondary heat exchanger fluidly connected to the heat transfer loop to exchange heat with the heat transfer fluid flowing through the heat transfer loop, the secondary heat exchanger being fluidly connected downstream of the engine-coolant-fluid heat exchanger and upstream of the fuel heat exchanger relative to the flow of the heat transfer fluid in the heat transfer loop, the secondary heat exchanger being thermally coupled to a ram air system, such that the heat transfer fluid flowing through the heat transfer loop transfers heat to the ram air system in order to provide significant cooling to the intercooler and aftercooler in the compress without causing a significant pressure drop by ensuring the temperature of the heat transfer fluid exits the fuel heat exchanger is below ambient temperature. Reasons for Indicating Potential Allowable Subject Matter The allowability of claim 1 depends on Applicant’s response regarding the 112a rejections, and such indication of potential allowable subject matter of claim 1 is because the prior arts themselves or in combination do not teach the limitation of claim 1 in combination with other limitation that requires a fuel heat exchanger thermally coupled to the condenser to receive heat from the combustion gases, the fuel heat exchanger located in the fuel delivery assembly to receive the fuel at cryogenic temperatures and heat the fuel by transferring the heat received from the combustion gases to the fuel; a heat transfer loop thermally coupling the condenser with the fuel heat exchanger in order to transfer the heat from the combustion gases to the fuel, the heat transfer loop including a heat transfer fluid flowing therethrough, the heat transfer fluid being subjected to the cryogenic temperatures when transferring heat to the fuel at the fuel heat exchanger, and a secondary heat exchanger fluidly connected to the heat transfer loop, being fluidly connected downstream of the condenser and upstream of the fuel heat exchanger relative to the flow of the heat transfer fluid in the heat transfer loop, and being thermally coupled to a separate engine system external to the fuel delivery assembly, such that the heat transfer fluid flowing through the heat transfer loop transfers heat to the separate engine system. 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 JINGCHEN LIU whose telephone number is (571)272-6639. The examiner can normally be reached 9:30-4:30. Examiner interviews are available via telephone, in-person, and video conferencing using a USPTO supplied web-based collaboration tool. To schedule an interview, applicant is encouraged to use the USPTO Automated Interview Request (AIR) at http://www.uspto.gov/interviewpractice. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Devon Kramer can be reached at (571) 272-7118. The fax phone number for the organization where this application or proceeding is assigned is 571-273-8300. Information regarding the status of published or unpublished applications may be obtained from Patent Center. Unpublished application information in Patent Center is available to registered users. To file and manage patent submissions in Patent Center, visit: https://patentcenter.uspto.gov. Visit https://www.uspto.gov/patents/apply/patent-center for more information about Patent Center and https://www.uspto.gov/patents/docx for information about filing in DOCX format. For additional questions, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). If you would like assistance from a USPTO Customer Service Representative, call 800-786-9199 (IN USA OR CANADA) or 571-272-1000. /JINGCHEN LIU/ /GERALD L SUNG/ Primary Examiner, Art Unit 3741 Examiner, Art Unit 3741
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Prosecution Timeline

Sep 08, 2023
Application Filed
Dec 04, 2024
Non-Final Rejection — §112
Mar 06, 2025
Response Filed
Apr 07, 2025
Applicant Interview (Telephonic)
Apr 08, 2025
Examiner Interview Summary
May 21, 2025
Response Filed
Jun 10, 2025
Final Rejection — §112
Aug 13, 2025
Applicant Interview (Telephonic)
Aug 13, 2025
Examiner Interview Summary
Sep 11, 2025
Request for Continued Examination
Sep 29, 2025
Response after Non-Final Action
Nov 20, 2025
Non-Final Rejection — §112
Feb 25, 2026
Response Filed
Mar 16, 2026
Final Rejection — §112 (current)

Precedent Cases

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

5-6
Expected OA Rounds
59%
Grant Probability
99%
With Interview (+62.0%)
2y 7m
Median Time to Grant
High
PTA Risk
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