Office Action Predictor
Last updated: April 16, 2026
Application No. 18/608,547

Turbomachine for an Aircraft Engine

Non-Final OA §103§112
Filed
Mar 18, 2024
Examiner
KIM, TAE JUN
Art Unit
3799
Tech Center
3700 — Mechanical Engineering & Manufacturing
Assignee
Mtu Aero Engines AG
OA Round
1 (Non-Final)
64%
Grant Probability
Moderate
1-2
OA Rounds
3y 8m
To Grant
83%
With Interview

Examiner Intelligence

Grants 64% of resolved cases
64%
Career Allow Rate
474 granted / 740 resolved
-5.9% vs TC avg
Strong +19% interview lift
Without
With
+19.0%
Interview Lift
resolved cases with interview
Typical timeline
3y 8m
Avg Prosecution
43 currently pending
Career history
783
Total Applications
across all art units

Statute-Specific Performance

§101
0.3%
-39.7% vs TC avg
§103
46.0%
+6.0% vs TC avg
§102
25.9%
-14.1% vs TC avg
§112
24.1%
-15.9% vs TC avg
Black line = Tech Center average estimate • Based on career data from 740 resolved cases

Office Action

§103 §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 . Drawings The drawings are objected to under 37 CFR 1.83(a). The drawings must show every feature of the invention specified in the claims. Therefore, the features of claim 9 must be shown or the feature(s) canceled from the claim(s). No new matter should be entered. Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance. Claim Rejections - 35 USC § 112 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. Claims 1-10 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. The claims are generally narrative and indefinite, failing to conform with current U.S. practice. They appear to be a literal translation into English from a foreign document and are replete with grammatical and idiomatic errors. Applicant’s claims are confusing as there appears to be defined an [overall] flow channel and any element that is in the [overall] flow channel appears to be recited, including those that are for the water flow rather than those for the gas flow. Accordingly, the claims are confusing as to the intended location of the different elements [e.g. flow element of Figs. 7a, 7b] as the [disclosed] location appears to be in the water flowpath, but the claim indicates they could be in the gas flowpath or the water flowpath. Similar issues occur for many of the elements of the claims. The claims are indefinite as the “at least two flow channels” of claim 5 does not recite any relationship with the “at least one flow channel” of claim 1 and its unclear whether of their relationship. It is unclear how to form “two flow channels” when there is nothing that distinguishes the two flow channels from each other in the claims. “facing the gas flow” is indefinite as there are many surfaces that face the gas flow, and it is unclear what applicant means as the gas surrounds the pipes 21 in Fig. 3 and there is no single direction facing the gas flow. Claim 8, “flow channels” lacks proper antecedent basis. 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. Claim(s) 1-5, 7, 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Johnson (4,569,195) in view of McGann (3,638,719) and optionally in view of Sterland (2,619,796). Johnson teaches A turbomachine for an aircraft propulsion drive, comprising: a compressor 28, 32, through which a gas flow streams in a flow direction of the turbomachine, a combustion chamber 36, a turbine 34, 30, 38, and a heat exchanger 48, 43 downstream of the turbine, wherein the heat exchanger is configured and arranged to produce steam from water by energy from the gas flow, which is fed to the gas flow for combustion with fuel in the combustion chamber, wherein the heat exchanger 48 has at least one flow channel 43, through which the water flows [from 42] and which has at least two sections [for 43] arranged parallel to one another, wherein the gas flow streams at an angle 49 through the at least two sections. (2) wherein the gas flow streams around the at least two sections [top and bottom 43 in heat exchanger 4848], one after the other, at an angle. (3) wherein a section of the at least one flow channel arranged further upstream in a flow direction of the gas flow. (4) wherein the at least one flow channel has at least one structural element [at least fins are shown] on its surface facing the gas flow. (5) wherein at least two flow channels are connected to one another by at least one structural element [fin or U-bend]. (7) wherein at least two sections of a flow channel [top and bottom 43] arranged parallel with respect to one another are in fluid connection by a connecting device [U-bend]. (8) wherein the connecting device is configured and arranged to divert water from a section of the flow channels into at least one adjacent section of the flow channels. Johnson does not teach the at least two sections, which comprise different materials, wherein a section of the at least one flow channel arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section arranged further downstream. McGann teaches the at least two sections 56, 58, 54, which comprise different materials; wherein a section of the at least one flow channel 56 or 58 arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section 54 arranged further downstream. McGann specifically teaches the materials of the heat exchanger should be arranged with the exotic and high temperature materials in the hot fluid and sequentially using less exotic materials in the cooler section in order to save money and/or weight [col. 2, lines 17-25]. Note that the forward portion 56 is columbium [density1 of 8.5 g/cm3], while the intermediate section 58 is steel [7.85 g/cm3], and downstreamost portion 54 is aluminum [2.7 g/cm3]. It would have been obvious to one of ordinary skill in the art to employ different materials for the two heat exchanger sections, wherein a section of the at least one flow channel arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section arranged further downstream, as taught by McGann, as the materials of the heat exchanger should be arranged with the exotic and high temperature materials in the hot fluid and sequentially using less exotic materials in the cooler section. The prior art already teach wherein the gas flow streams at an angle through the at least two sections; (2) wherein the gas flow streams around the at least two sections, one after the other, at an angle [includes zero according to applicant’s specification]. For an alternate treatment of this limitation, Sterland [Fig. 1] teaches wherein the gas flow streams at an angle through the at least two sections 9; (2) wherein the gas flow [from 5] streams around the at least two sections 9, one after the other, at an angle [enters from 5 and exits from the top of 9 in Fig. 1], where the offset between the entry and exit increases the time in the heat exchanger and allows for greater effectiveness of the heat transfer. It would have been obvious to one of ordinary skill in the art to make the gas flow streams at an [non-zero] angle through the at least two sections; (2) wherein the gas flow streams around the at least two sections, one after the other, at an angle, as taught by Sterland, as typically done in the art to create an offset between the entry and exit, which increases the time in the heat exchanger and allows for greater effectiveness of the heat transfer. Claim(s) 1-8, 10 is/are rejected under 35 U.S.C. 103 as being unpatentable over FR 3144195 in view of Johnson (4,569,195) in view of McGann (3,638,719) and optionally in view of Sterland (2,619,796). FR ‘195 teaches A turbomachine for an aircraft propulsion drive, comprising: a compressor 2A, through which a gas flow streams in a flow direction of the turbomachine, a combustion chamber 3, a turbine 3, and a heat exchanger 10 downstream of the turbine 3, wherein the heat exchanger is configured and arranged to produce heated coolant by energy from the gas flow 8, which is fed to the gas flow for combustion with fuel in the combustion chamber, wherein the heat exchanger 10 has at least one flow channel 7, 8 through which the coolant 7, 17 flows and which has at least two sections arranged parallel to one another [top and bottom in the radially direction in Fig. 1, 2], wherein the gas flow streams at an angle through the at least two sections [radially outside in Fig. 1, 2], (2) wherein the gas flow streams around the at least two sections, one after the other [radially outwardly in Figs. 1, 2], at an angle. (4) wherein the at least one flow channel 20 has at least one structural element [e.g. fins] on its surface facing the gas flow 8. (5) wherein at least two flow channels are connected to one another by at least one structural element [26 or 25]. (6) wherein at least two sections of the at least one flow channel have different inner cross sections [compare finned area 18 vs return area 25 in Figs. 5-7]. (7) wherein at least two sections of a flow channel arranged parallel with respect to one another are in fluid connection by a connecting device 25. (8) wherein the connecting device 25 is configured and arranged to divert coolant from a section of the flow channels into at least one adjacent section of the flow channels. (10) wherein the at least one flow channel 18 or 20 has a flow element [e.g. fins 18a or 28]. FR ‘195 teaches the coolant is air and does not teach the coolant is water by which the heat exchanger is configured and arranged to produce steam from water by energy from the gas flow, which is fed [water/steam injected] to the gas flow for combustion with fuel in the combustion chamber. Johnson teaches an analogous arrangement of heat exchanger by which the heat exchanger is configured and arranged to produce steam from water by energy from the gas flow, which is fed to the gas flow for combustion with fuel in the combustion chamber in a manner that increases power output, efficiency and/or reduces combustion emissions [paragraph bridging cols. 6, 7]. It would have been obvious to one of ordinary skill in the art to make the coolant of FR ‘195, water, by which steam is produced and fed to the gas flow for combustion, as taught by Johnson, in order to increase power output, efficiency and/or reduce combustion emissions. FR ‘195 does not teach the at least two sections, which comprise different materials, wherein a section of the at least one flow channel arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section arranged further downstream. McGann teaches the at least two sections 56, 58, 54, which comprise different materials; wherein a section of the at least one flow channel 56 or 58 arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section 54 arranged further downstream. McGann specifically teaches the materials of the heat exchanger should be arranged with the exotic and high temperature materials in the hot fluid and sequentially using less exotic materials in the cooler section in order to save money and/or weight [col. 2, lines 17-25]. Note that the forward portion 56 is columbium [density2 of 8.5 g/cm3], while the intermediate section 58 is steel [7.85 g/cm3], and downstreamost portion 54 is aluminum [2.7 g/cm3]. It would have been obvious to one of ordinary skill in the art to employ different materials for the two heat exchanger sections, wherein a section of the at least one flow channel arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section arranged further downstream, as taught by McGann, as the materials of the heat exchanger should be arranged with the exotic and high temperature materials in the hot fluid and sequentially using less exotic materials in the cooler section. The prior art already teach wherein the gas flow streams at an angle through the at least two sections; (2) wherein the gas flow streams around the at least two sections, one after the other, at an angle [includes zero according to applicant’s specification]. For an alternate treatment of this limitation, Sterland [Fig. 1] teaches wherein the gas flow streams at an angle through the at least two sections 9; (2) wherein the gas flow [from 5] streams around the at least two sections 9, one after the other, at an angle [enters from 5 and exits from the top of 9 in Fig. 1], where the offset between the entry and exit increases the time in the heat exchanger and allows for greater effectiveness of the heat transfer. It would have been obvious to one of ordinary skill in the art to make the gas flow streams at an [non-zero] angle through the at least two sections; (2) wherein the gas flow streams around the at least two sections, one after the other, at an angle, as taught by Sterland, as typically done in the art to create an offset between the entry and exit, which increases the time in the heat exchanger and allows for greater effectiveness of the heat transfer. Claim(s) 1-5, 7, 8 is/are rejected under 35 U.S.C. 103 as being unpatentable over Klingels (WO 2022028653, note all citations are from US 2023/0286661) Johnson (4,569,195) in view of McGann (3,638,719) and optionally in view of Sterland (2,619,796). Klingels teaches A turbomachine for an aircraft propulsion drive, comprising: a compressor 13, through which a gas flow streams in a flow direction of the turbomachine, a combustion chamber 16, a turbine 17, and a heat exchanger 30 downstream of the turbine, wherein the heat exchanger 30 is configured and arranged to produce steam from water by energy from the gas flow, which is fed to the gas flow for combustion with fuel in the combustion chamber, wherein the heat exchanger 30 has at least one flow channel, through which the water flows and which has at least two sections arranged parallel to one another [e.g. different modules of different dimeters, ¶ 0086], wherein the gas flow streams at an angle through the at least two sections. (2) wherein the gas flow streams around the at least two sections 30, one after the other, at an angle. (4) wherein the at least one flow channel has at least one structural element on its surface facing the gas flow. (5) wherein at least two flow channels are connected to one another by at least one structural element 31. (7) wherein at least two sections of a flow channel arranged parallel with respect to one another are in fluid connection by a connecting device. (8) wherein the connecting device is configured and arranged to divert water from a section of the flow channels into at least one adjacent section of the flow channels. Klingels does not teach the at least two sections, which comprise different materials, wherein a section of the at least one flow channel arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section arranged further downstream. McGann teaches the at least two sections 56, 58, 54, which comprise different materials; wherein a section of the at least one flow channel 56 or 58 arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section 54 arranged further downstream. McGann specifically teaches the materials of the heat exchanger should be arranged with the exotic and high temperature materials in the hot fluid and sequentially using less exotic materials in the cooler section in order to save money and/or weight [col. 2, lines 17-25]. Note that the forward portion 56 is columbium [density3 of 8.5 g/cm3], while the intermediate section 58 is steel [7.85 g/cm3], and downstreamost portion 54 is aluminum [2.7 g/cm3]. It would have been obvious to one of ordinary skill in the art to employ different materials for the two heat exchanger sections, wherein a section of the at least one flow channel arranged further upstream in a flow direction of the gas flow comprises a material with a higher density than a section arranged further downstream, as taught by McGann, as the materials of the heat exchanger should be arranged with the exotic and high temperature materials in the hot fluid and sequentially using less exotic materials in the cooler section. The prior art already teach wherein the gas flow streams at an angle through the at least two sections; (2) wherein the gas flow streams around the at least two sections, one after the other, at an angle [includes zero according to applicant’s specification]. For an alternate treatment of this limitation, Sterland [Fig. 1] teaches wherein the gas flow streams at an angle through the at least two sections 9; (2) wherein the gas flow [from 5] streams around the at least two sections 9, one after the other, at an angle [enters from 5 and exits from the top of 9 in Fig. 1], where the offset between the entry and exit increases the time in the heat exchanger and allows for greater effectiveness of the heat transfer. It would have been obvious to one of ordinary skill in the art to make the gas flow streams at an [non-zero] angle through the at least two sections; (2) wherein the gas flow streams around the at least two sections, one after the other, at an angle, as taught by Sterland, as typically done in the art to create an offset between the entry and exit, which increases the time in the heat exchanger and allows for greater effectiveness of the heat transfer. Claim(s) 6, 9, 10 is/are rejected under 35 U.S.C. 103 as being unpatentable over any of the prior art, as applied above, and further in view of art above, and further in view of Ziron (3201938). The prior art do not teach (9) wherein a number of first sections differ from a number of second sections of the heat exchanger. Ziron teaches the number of first inner sections 45 differ from a number of second sections 47 of the heat exchanger in a gas turbine engine, as a typical matter of using the workable ranges in the art to fill a heat exchange region with sections. It would have been obvious to one of ordinary skill in the art to employ a number of first sections [that] differ from a number of second sections of the heat exchanger, as taught by Ziron, as a typical matter of using the workable ranges in the art to fill a heat exchange region with sections. The prior art do not necessarily teach (10) wherein the at least one flow channel has a flow element Ziron teaches each wherein the at least one flow channel has a flow element 45, 47 [finned structure] to facilitate heat transfer. It would have been obvious to one of ordinary skill in the art to employ flow element / finned structure, as taught by Ziron, in order to facilitate heat transfer. The prior art do not necessarily teach (6) wherein at least two sections of the at least one flow channel have different inner cross sections. Ziron teaches (6) wherein at least two sections 41 or 45 or 40 or 47 or 46 of the at least one flow channel have different inner cross sections as a obvious matter of using differing cross sections depending on desired flow rates and heat exchange rates. It would have been obvious to one of ordinary skill in the art to employ different cross sections as an obvious matter of using differing cross sections depending on desired flow rates and heat exchange rates. Claim(s) 6-10 is/are rejected under 35 U.S.C. 103 as being unpatentable over any of the prior art, as applied above, and further in view of art above, and further in view of Holm (2,650,073). The prior art do not necessarily teach (6) wherein at least two sections of the at least one flow channel have different inner cross sections. (7) wherein at least two sections of a flow channel arranged parallel with respect to one another are in fluid connection by a connecting device. (8) wherein the connecting device is configured and arranged to divert water from a section of the flow channels into at least one adjacent section of the flow channels. (9) wherein a number of first sections differ from a number of second sections of the heat exchanger. (10) wherein the at least one flow channel has a flow element. Holm teaches (6) wherein at least two sections of the at least one flow channel have different inner cross sections [54 vs 55 have different cross sections]. (7) wherein at least two sections of a flow channel arranged parallel with respect to one another are in fluid connection by a connecting device [header, akin to 29, but for the water flow 52]. (8) wherein the connecting device [header] is configured and arranged to divert water from a section of the flow channels into at least one adjacent section of the flow channels. (9) wherein a number of first sections [outer 41] differ from a number of second sections [20] of the heat exchanger. (10) wherein the at least one flow channel has a flow element. 61. Holm’s heat exchanger is used between gas turbine exhaust and water [see col. 1] It would have been obvious to one of ordinary skill in the art to employ (6) wherein at least two sections of the at least one flow channel have different inner cross sections; (7) wherein at least two sections of a flow channel arranged parallel with respect to one another are in fluid connection by a connecting device; (8) wherein the connecting device is configured and arranged to divert water from a section of the flow channels into at least one adjacent section of the flow channels; (9) wherein a number of first sections differ from a number of second sections of the heat exchanger; (10) wherein the at least one flow channel has a flow element, in the manner taught by Holm, as typical heat exchange structure used in the art to exchange heat between gas turbine exhaust and water that is utilized in the art. Contact Information Any inquiry concerning this communication or earlier communications from the Examiner should be directed to TED KIM whose telephone number is 571-272-4829. The Examiner can be reached on regular business hours before 5:00 pm, Monday to Thursday and every other Friday. The fax number for the organization where this application is assigned is 571-273-8300. If attempts to reach the examiner by telephone are unsuccessful, the examiner’s supervisor, Boyer Ashley, can be reached at 571-272-4502. Alternate inquiries to Technology Center 3700 can be made via 571-272-3700. Information regarding the status of an application may be obtained from Patent Center https://www.uspto.gov/patents/apply/patent-center. Should you have questions on Patent Center, contact the Electronic Business Center (EBC) at 866-217-9197 (toll-free). General inquiries can also be directed to the Inventors Assistance Center whose telephone number is 800-786-9199. Furthermore, a variety of online resources are available at https://www.uspto.gov/patent /Ted Kim/ Telephone 571-272-4829 Primary Examiner Fax 571-273-8300 August 8, 2025 1 Densities are commonly available from the internet and handbooks. 2 Densities are commonly available from the internet and handbooks. 3 Densities are commonly available from the internet and handbooks.
Read full office action

Prosecution Timeline

Mar 18, 2024
Application Filed
Aug 08, 2025
Non-Final Rejection — §103, §112
Apr 13, 2026
Response after Non-Final Action

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1-2
Expected OA Rounds
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Grant Probability
83%
With Interview (+19.0%)
3y 8m
Median Time to Grant
Low
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