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 .
This is in response to the amendments filed on 1/27/2026 and Request for Continued Examination (RCE) filed on 2/25/2026.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 2/25/2026 has been entered.
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.
Claim 1, and its dependent claims, 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.
In claim 1: the limitation “the exhaust being disposed at a rear side of the hydrogen-burning gas turbine engine” does not appear to be supported by the Specification and Drawings, it is considered new matter. Additional comments in the Response to Arguments/Remarks section at the end of this OC.
Claim Rejections - 35 USC § 103
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.
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.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1, 8 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Boucher 20210340908 in view of Fisher 20150377159, Tapie 20150107217, Durocher 20220349343 and Shekleton 5095694 and Ledwith 11905914
Regarding claim 1, Boucher teaches:
A gas turbine engine system (Abstract) comprising:
a hydrogen-burning gas turbine engine ([0017]) with a combustion apparatus (image below from Boucher Fig. 4) and a fuel system (420, Fig. 4);
a fuel line (Fig 4, line 426 from 422) arranged to receive gaseous hydrogen (hydrogen [0003]) at an input thereof (connecting point with 422, Fig 4) and provide the gaseous hydrogen to the combustion apparatus (Fig 4, 412 combustor).
a vent line (from 456 to 454) including a vent valve (456 in Fig 4 represents the vent valve; indicated in Image CL1 below) and having a first end coupled to the fuel line (at the vent valve) and a second end disposed remotely from the hydrogen-burning gas turbine engine (passing to APU 450, then to 454), the vent line being arranged and configured to direct the gaseous hydrogen away from the combustion apparatus (Fig 4 shows flow from 456 through 450, 452 and then to exhaust overboard 454 [0052]), the vent line being separate from the fuel line (Fig 4)
the exhaust being disposed at a rear side of the hydrogen-burning gas turbine engine (inter alia, right side of Fig. 1);
a shut-off valve disposed at the input of the fuel line (Fig 4, flow controller 424: “flow controller 424 may be controlled to direct a fuel from the cryogenic fuel tank 422 through the first flow supply line 426 for certain operational parameters, through the second flow supply line 428 for other operational parameters, and through the third flow supply line 444 for other operational parameters” [0050], valve 424 can direct flow to specific supply lines, therefore being able to shut off fuel to other lines as needed; Fig 4 shows 424 at the input of the fuel line);
Boucher is silent about the vent line directly connecting the combustion apparatus to an exhaust of the hydrogen-burning gas turbine engine, as claimed, and the controller as claimed.
However, Fisher teaches a fuel system, where a “multi-fuel capable engines may include a gas turbine” [0021], operating on gaseous hydrogen [0014] and comprising a storage tank 212 (fig. 4) connected via 216 and a fuel line 114 (Fig. 4), and:
a vent line (436, a gaseous fuel vent line [0060], Fig. 4) including a vent valve (448) and having a first end coupled to the fuel line (left end, Fig. 4) and a second end disposed remotely from the hydrogen-burning engine (right end), the vent line being arranged and configured to direct the gaseous hydrogen away from the combustion apparatus (Fig 4 shows flow “to atmosphere), the vent line being separate from the fuel line (Fig. 4)
the vent line (436, a gaseous fuel vent line [0060], Fig. 4) directly connecting the combustion apparatus (inter alia, 118 Fig. 4) to an exhaust (Right side of 436, “to atmosphere”, Fig. 4) of the hydrogen-burning (hydrogen [0014]) engine (118 Fig. 4);
a controller (a control system, Abstract; 136 [0072, 0095]) configured to shut down (paragraph [0099] discusses Method 900 of Fig. 9 and further discusses procedures to be taken in case of system degradations, i.e., emergency shutdown) the gas turbine engine ([0021]) by:
(i) opening the vent valve (a vent valve in a passage fluidically coupling the gaseous fuel supply line to atmosphere may be opened, such as valve 448, to quickly purge the gaseous fuel to atmosphere [0099]) in response to a detection of an abnormal condition (“degradation of a turbocharger or other vehicle or engine component is detected”, “emergency shutdown” [0099]) in the hydrogen-burning engine, such that the gaseous hydrogen (hydrogen [0014]) evacuated from the combustion apparatus (in this case, evacuated through Boucher 456), and flows through the vent line and the vent valve (a vent valve in a passage fluidically coupling the gaseous fuel supply line to atmosphere may be opened, such as valve 448, to quickly purge the gaseous fuel to atmosphere [0099]), so as to be directed away from the combustion apparatus (“purge the gaseous fuel to atmosphere” [0099], therefore away from the combustion apparatus, see Fig. 4), and
(ii) closing the shut-off valve (step 902, Fig 9 as associated to Method 900, and additional steps discussed in [0099] related to an emergency shutdown) at the input of the fuel line in response to the detection of the abnormal condition in the hydrogen-burning engine ([0099]), when the vent valve is switched from a closed state to an open state (Fisher [0099] teaches the need for an immediately shutdown to prevent catastrophic damage, when “operating at idle to vent the gaseous fuel to the engine may not be desired. Accordingly, a vent valve in a passage fluidically coupling the gaseous fuel supply line to atmosphere may be opened” [0099]).
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Boucher with Fisher's teachings discussed above, so that “during certain conditions, such as if degradation of […] vehicle or engine component is detected, the engine may be immediately shutdown to prevent catastrophic damage to the engine or vehicle” as taught by Fisher [0099].
Furthermore, and to remove any doubt, Tapie teaches a vent system for a gas turbine (title), comprising a fuel supply circuit for gaseous fuel, and outlets 13 to provide the combustion chamber with gaseous fuel, and a routing line 14 connecting the inlet 12 with the outlets 13 ([0028]), and:
a vent line (inter alia, 31, 30, Fig. 2) including a vent valve (32) and having a first end coupled to the fuel line (bottom end, Fig. 2) and a second end disposed remotely from the gas turbine engine (top end), the vent line being arranged and configured to direct the gaseous away from the combustion apparatus (Fig 2, venting to 30), the vent line being separate from the fuel line (Fig. 2)
the vent line (vertical line below 32, Fig. 2) directly connecting the combustion apparatus (inter alia, elements to the right of the vent line in Fig. 2, 17, 13) to an exhaust of the gas turbine engine (a secondary vent 30 towards the atmosphere [0039], Fig. 2; it is noted that a broad interpretation of exhaust would include a merriam-webster dictionary definition of exhaust as “1 a: the escape of used gas or vapor from an engine b: the gas or vapor escaping from an engine; 2 a: the conduit through which used gases escape b: an arrangement for removing fumes, dusts, or odors from an enclosure”);
a controller (33) configured to shut down the gaseous fuel burning gas turbine engine (abstract) by:
(i) opening the vent valve (valve 32 is opened [0045]) in response to a detection of an abnormal condition (in case of emergency shutdown [0045]) in the gas turbine engine, such that the gaseous [fuel] evacuated from the combustion apparatus (Image below from Tapie Fig. 2), and flows through the vent line and the vent valve (to vent towards the atmosphere the gaseous fuel remaining [0045]), so as to be directed away from the combustion apparatus (“vent 30 towards the atmosphere” [0039], see Fig. 2), and
(ii) closing the shut-off valve at the input of the fuel line in response to the detection of the abnormal condition in the gas turbine engine (the valves 15, 16 and 17 of the routing line are all closed [0045]), when the vent valve is switched from a closed state to an open state ([0045]).
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Boucher in view of Fisher with Tapie's teachings discussed above in order to shutdown the gas turbine in case of an emergency shutdown, as taught by Tapie [0045].
Furthermore, Boucher teaches exhausting gases overboard (see 454 in Fig 4, which is placed near the exhaust of the aircraft 418 in Fig. 4), and to remove any doubt, Durocher 20220349343 and Shekleton 5095694 and Ledwith 11905914 also address fuel vent lines:
Durocher also teaches:
the vent line (inter alia, sweep line structure, abstract; “(inter alia, sweep line structure, abstract)” [0050]) directly connecting the combustion apparatus (inter alia, combustor via nozzle manifold, Fig. 3) to an exhaust of the hydrogen-burning gas turbine engine (see H2 nozzle, Fig. 3), the exhaust being disposed at a rear side of the hydrogen-burning gas turbine engine (inter alia, right side of Fig. 1);
and Shekleton teaches:
the vent line (inter alia, pure line 66) directly connecting the combustion apparatus (inter alia, 22) to an exhaust of the gas turbine engine (see 68 in Fig. 1, “A purge line 66 is connected to the outlet port 48 of each of the valves 42, 44 and extends into an exhaust conduit 20 of a turbine engine” abstract),
and Ledwith also teaches:
the vent line (104, Fig. 4) to an exhaust of the hydrogen-burning gas turbine engine (see exhaust wall 50, Fig. 4), the exhaust being disposed at a rear side of the hydrogen-burning (title) gas turbine engine (Fig. 1);
It would have been obvious to a person having ordinary skills in the art before the effective filing date of the claimed invention to provide Boucher in view of Fisher and Tapie with Durocher, Shekleton 5095694 and Ledwith's teachings discussed above in order to “direct “hydrogen vapor (e.g., H.sub.2 gas)” “into the exhaust to be burnt off; e.g., where the combustion products directed out of the combustor 30 include some leftover fluid oxygen (e.g., O.sub.2 gas)”, as taught by Durocher Col 9 ll. 14-20, so it can be properly vented from the system.
PNG
media_image1.png
751
852
media_image1.png
Greyscale
PNG
media_image2.png
869
1140
media_image2.png
Greyscale
Regarding claim 8, Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith teaches the invention as discussed for claim 1. Boucher further teaches:
wherein the fuel system further comprises a store of liquid hydrogen (Fig 4, element 422) and an evaporator (Fig 4, elements 432 and 434 receive the fuel from cryogenic tank 422 and add heat at 432 and expand it at 434) arranged to receive and evaporate liquid hydrogen from the store and provide gaseous hydrogen to the input of the fuel line (Fig 4).
Regarding claim 12, Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith teaches the invention as discussed for claim 1. Boucher teaches:
An aircraft (commercial and military aircraft [0002]) comprising a gas turbine engine system ([0002-0034]) according to claim 1 (Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith teaches the invention as discussed for claim 1).
Claim 6 is rejected under 35 U.S.C. 103 as being unpatentable over Boucher 20210340908 in view of Fisher 20150377159, Tapie 20150107217, Durocher 20220349343 and Shekleton 5095694 and Ledwith 11905914 and further in view of Epstein 2015/0344143.
Regarding claim 6, Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith teaches the invention of claim 1.
Boucher teaches:
the fuel system further comprises a store of [liquid] hydrogen (element 422) coupled to the input of the fuel line (Fig 4), the [liquid] hydrogen being compressed inside the store (“liquid/compressed/supercritical hydrogen” [0049])
Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith is silent about:
The store being a store of compressed gaseous hydrogen.
However, Epstein teaches a method for managing evaporated cryogenic fuel (Epstein Title) and the fuel system comprising a store of liquid cryogenic fuel that is also a store of compressed gaseous cryogenic fuel due to vaporization during storage:
the fuel system further comprises a store of liquid cryogenic fuel that is also a store of compressed gaseous cryogenic fuel coupled to the input of the fuel line, the gaseous cryogenic fuel being compressed inside the store (“a storage tank of a cryogenic fuel system of an aircraft, including venting gas in the form of evaporated cryogenic fuel from the storage tank to maintain an internal pressure in the storage tank” [0006], “a cryogenic fuel tank 122 capable of storing a cryogenic liquid fuel 112” [0035], and it is noted the tank contains liquid cryogenic fuel which is stored compressed in order to maintain its state), the store coupled to the input of the fuel line (“gaseous fuel 19 may be supplied to the aircraft propulsion system” Epstein [0048]).
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith with Epstein's structure discussed above, so the fuel system further comprises a store of gaseous hydrogen coupled to the input of the fuel line, the gaseous hydrogen being compressed inside the store, in order to make efficient use of the cryogenic fuel, to include using the evaporated cryogenic fuel in the storage tanks such that “gases may be utilized in several useful ways in the aircraft system […] For example at least a portion of the gaseous fuel 19 may be supplied to the aircraft propulsion system 100 for […] combustion in the engine” as taught by Epstein [0048]
Claims 9 and 10 are rejected under 35 U.S.C. 103 as being unpatentable over Boucher 20210340908 in view of Fisher 20150377159, Tapie 20150107217, Durocher 20220349343 and Shekleton 5095694 and Ledwith 11905914 and Beauchesne-Martel 20230251165.
Regarding claim 9, Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith teaches the invention of claim 1. Boucher teaches the hydrogen-burning gas turbine engine, as already discussed.
Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith is silent about the abnormal condition is a shaft-break, as claimed.
However, Beauchesne-Martel teaches a gas turbine engine (Fig. 1) and “a method of detecting a shaft shear event occurring at a shaft of an engine” [0004], :
the abnormal condition is a shaft-break (“Depending on the location of the shear 36, the turbine portion 16 can remain properly supported by bearings and be free to rotate independently of the load 26, 12, which may lead to over-speeding, and which can be avoided by shutting down the energy source to the engine” [0024]; a controller (Beauchesne-Martel [0027]: engine controller 92) arranged to “shut[] down the engine, e.g. closing off a valve associated to a fuel supply, in reaction to the early indication of shaft shear” [0003] "by directly controlling a fuel control valve" [0027], “a shaft shear mitigation module 98 can further be responsible for controlling shutting down the engine in the event of shaft shear detection, such as by directly controlling a fuel control valve, or indirectly, by sending a signal to a fuel control module 99” [0027])
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith with Beauchesne-Martel’s teachings discussed above to avoid “over-speeding, and which can be avoided by shutting down the energy source to the engine” [0024] and therefore protect other portions of the system.
Regarding claim 10, Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith teaches the invention of claim 1. Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith, as discussed so far, is silent about:
the controller is a Full-Authority Digital Electronic Controller of the hydrogen-burning gas turbine engine.
However, Beauchesne-Martel teaches a gas turbine engine (Fig. 1) and:
the controller is a Full-Authority Digital Electronic Controller (“full authority digital engine controller (FADEC)” Beauchesne-Martel [0075]) of the hydrogen-burning gas turbine engine.
It would have been obvious to a person having ordinary skill the art before the effective filing date of the claimed invention to provide Boucher in view of Fisher, Tapie, Durocher, Shekleton and Ledwith with Beauchesne-Martel’s structure as discussed above in order to have an automated system to shutdown the engine and avoid over-speeding and turbine bursting, as taught by Beauchesne-Martel [0002-0003].
Response to Arguments/Remarks
Applicant’s arguments dated 1/27/2026 have been considered, but they are not persuasive because they do not apply to the new combination of references, i.e., adding a new reference to the old combination of references, that was necessitated by applicant’s amendment. However, to the extent possible, applicant’s arguments have been addressed in the body of the rejections above, at the appropriate location.
Remarks regarding the interview granted on 17 December 2025
In the remarks, Applicant noted on page 5:
PNG
media_image3.png
153
970
media_image3.png
Greyscale
Examiner’s response: If Applicant representative had the impression that the merits of the arguments were not addressed, that was not the intention. Examiner Igue and Primary Examiner Meade made their best attempt to fully address the Applicant’s questions and explain, as stated in the Examiner Interview Summary Record, that examiners have to apply the broadest reasonable interpretation to the limitation, in this case the “exhaust”. However, applicant’s interpretation of the word and expectations did not seem to match the interpretation explained by the examiners.
Remarks regarding Amendments
It is noted that Applicant provides the following comments in the Remarks dated 1/27/2026, stating the “added limitation is inherently supported by the specification” (blow is page 6 of Applicant’s remarks):
PNG
media_image4.png
1250
1018
media_image4.png
Greyscale
Examiner’s response: Applicant’s remarks have been carefully considered, but the examiner respectfully disagrees. The Image provided by Applicant in the remarks does not appear to be part of the present application, and there its source was not disclosed in the remarks. Below is an image of a Gas Turbine Engine Pratt & Whitney’s PT6A, presented as a counter-argument to Applicant’s remarks:
PNG
media_image5.png
834
1433
media_image5.png
Greyscale
Source: https://web.archive.org/web/20230522160802/https://www.aopa.org/news-and-media/all-news/2018/march/pilot/turbine-denali-pt6
Labels were added to improve readability. The front of the engine is on the left side of the figure, where “propeller mounting flange” is located. The exhaust stack is located forward of the turbines and compressor. This design was known in the art, as evidenced by the same website listed above:
PNG
media_image6.png
254
1341
media_image6.png
Greyscale
Applicant argues on page 9:
PNG
media_image7.png
161
1008
media_image7.png
Greyscale
Examiner’s response: The base reference used in the previous and the present rejection is Boucher 20210340908. Boucher is not explicit but hints to the placement of a vent 454 connected or in proximity to the exhaust (see Fig 4 and discussion in the rejection). The added references fully address the remark above.
Correspondence
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Roberto T. Igue whose telephone number is (303)297-4389. The examiner can normally be reached Monday-Friday 7:30-4:30 PT.
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, Phutthiwat Wongwian can be reached on (571) 270-5426. 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.
/ROBERTO TOSHIHARU IGUE/ Examiner, Art Unit 3741
/PHUTTHIWAT WONGWIAN/ Supervisory Patent Examiner, Art Unit 3741
Prosecution Insights