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 .
Claims 1-4, 6-10 and 12 are currently being examined.
Election/Restrictions
Claim 21 had been withdrawn from further consideration pursuant to 37 CFR 1.142(b) in the office action filed 01/07/2026, as being drawn to a nonelected species, there being no allowable generic or linking claim. Once withdrawn, claims cannot be amended to be rejoined for further examination. Claim 21 stands as withdrawn.
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, 6-10 and 12 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.
Claim 1 recites “a valve configured to control flow of the fuel, from a pipe with a first end at an outlet of the primary fuel-oil heat exchanger to a second end at the valve without increasing pressure through the pipe” which is not supported by the original disclosure.
In patent application publication 20250198343 of the instant application, specification [0121] describes a valve operable to enable fuel to recirculate through a primary heat exchanger and [0123] describes for any of the recirculation valves described herein, there may be one or more associated pumps configured to convey fuel back to the inlet of the heat exchanger or any suitable components for repressurizing the fuel to enable recirculation may be used. Regarding the elected Species II-5 drawn to Fig. 19, [0412] describes that recirculation pipe 1206 may comprise or is associated with one or more pumps configured to convey fuel through 1206, with the pumps positioned upstream of second valve 1202 or anywhere along 1206. The original disclosure, therefore, describes pressurizing flow of the fuel between primary heat exchanger 1220 and second valve 1202 and/or pressurizing the flow of the fuel downstream of second valve 1202; but the original disclosure does not describe fuel flow in a pipe with a first end at an outlet of primary fuel-oil heat exchanger 1220 to a second end at second valve 1202 “without increasing pressure through the pipe.”
In addition, claim 1 also claims “a fuel supply system, wherein the fuel supply system is arranged to supply fuel for combustion in the combustor, and to supply fuel to fueldraulically drive at least one actuator of the plurality of actuators.” As described in the specification:
[0330] “The fuel supply system 152 is arranged to supply fuel for combustion in the combustor 16.”
[0331] “It will be appreciated that one or more valves, pumps, sensors, offtakes for fueldraulic actuators, and heat exchangers may be present along the main fuel flow path 110, among other engine components. Fuel is supplied to the combustor 16 directly via line 110a, after passing through whichever prior engine component along the main fuel flow path 110 is furthest downstream."
[0447]: “One or more valves may be used to control the fuel flow rate through the, or each, fueldraulic fuel flow loop. In some implementations, one or more fueldraulic fuel pumps may be provided to actively pump the fuel to or from the at least one actuator 354—however, in many implementations, the pressure provided by one or more fuel pumps on the main fuel flow path 110 may suffice.”
Such fuel supply pump(s) can increase fuel pressure upstream of the primary fuel-oil heat exchanger and the claimed pipe, resulting in increasing pressure through the pipe.
In addition, specification [0464] describes “The heat transfer ratio may be controlled by opening and closing valves so as to enable: fuel recirculation through either or both of heat exchangers 1220, 1230, fuel bypass of either or both of the heat exchangers 1220, 1230, oil recirculation through either or both of the heat exchangers 1220, 1230, or oil bypass of either or both of the heat exchangers 1220, 1230.” Closing second valve 1202 would cause surge pressure, i.e., a pressure wave causing an increase in pressure in the flow of the fuel through the pipe upstream of 1202. (see attached NPL – A Quick Guide to Pipeline Engineering)
Claims dependent upon claim 1 are rejected as failing to comply with the written description requirement for the same reasons as claim 1.
Claims 1-4, 6-10 and 12 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 enablement requirement. The claim(s) contains subject matter which was not described in the specification in such a way as to enable one skilled in the art to which it pertains, or with which it is most nearly connected, to make and/or use the invention.
Claim 1 recites “a valve configured to control flow of the fuel, from a pipe with a first end at an outlet of the primary fuel-oil heat exchanger to a second end at the valve without increasing pressure through the pipe.”
The standard for determining whether the specification meets the enablement requirement was cast in the Supreme Court decision of Minerals Separation V. Hyde, 242 U.S. 261, 270 (1916) which posed the question: is the experimentation needed to practice the invention undue or unreasonable? That standard is still the one to be applied. In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988).
Determining enablement is a question of law based on underlying factual findings. In re Vaeck, 947 F.2d 488, 495 (Fed. Cir. 1991). The determination that "undue experimentation" would have been needed to make and use the claimed invention is not a single, simple factual determination. Rather, it is a conclusion that may be reached by weighing some or all of the following non-exhaustive list of factual considerations: (A) the breadth of the claims (in this case, a gas turbine engine for an aircraft including a fuel supply system); (B) the nature of the invention (in this case, a fuel supply system including a plurality of actuators, primary and secondary fuel-oil heat exchangers and a valve with three outlets directing fuel flow through three different paths for controlling fuel temperature); (C) the state of the prior art (prior art of record Sabnis teaches with reference to Fig. 1 an gas turbine engine for an aircraft including components of an engine core and a fuel system; and prior art of record Clements teaches with reference to Fig. 2 a fuel supply system is arranged to supply fuel to fueldraulically drive at least one actuator of the plurality of actuators; a primary fuel-oil heat exchanger arranged to have oil and the fuel flow therethrough, the primary fuel-oil heat exchanger being arranged to transfer heat from the oil to the fuel; and a valve configured to control flow of the fuel from an outlet of the primary fuel-oil heat exchanger through three different outlets of the valve, (i) a first valve outlet that directs the flow of fuel through a recirculation pipe configured to direct the fuel back through the primary fuel-oil heat exchanger, (ii) a second valve outlet that directs the flow of the fuel to a combustor, and (iii) a third valve outlet that directs the flow of the fuel to a secondary fuel-oil heat exchanger; wherein the primary fuel-oil heat exchanger is arranged such that, at cruise, the fuel temperature on entry into the at least one actuator is at least 5°C greater than the fuel temperature on entry to the combustor); (D) the level of one of ordinary skill; (E) the level of predictability in the art; (F) the amount of direction provided by the inventor (in this case, the original disclosure does not provide how to have fuel flow not increase through the claimed pipe); (G) the existence of working examples (in this case, no working examples are provided); and (H) the quantity of experimentation needed to make or use the invention based on the content of the disclosure (in this case, due to the lack of description (see 112(a) rejection for lack of written description above) of how to have fuel flow not increase through the claimed pipe, one of ordinary skill would not be able to make or use the invention without undue experimentation). Wands, 858 F.2d at 737.
Therefore, claim 1 is rejected as failing to comply with the enablement requirement.
Claims dependent upon claim 1 are rejected as failing to comply with the enablement requirement for the same reasons as base claim 1.
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 1-4, 6-10 and 12 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.
Claim 1 recites “a valve configured to control flow of the fuel, from a pipe with a first end at an outlet of the primary fuel-oil heat exchanger to a second end at the valve without increasing pressure through the pipe” which is unclear, in light of the remaining limitations of claim 1 and in light of a lack of description in the original disclosure, as to how “without increasing pressure through the pipe” is accomplished, such that the claim scope is indefinite and one of ordinary skill in the art is unable to determine whether or not another invention infringes upon the claim.
Since the scope of claim 1 is indefinite and cannot be clearly determined, claims 1-4, 6-10 and 12 cannot be examined over the prior art.
Response to Arguments
Applicant's arguments filed 04/07/2026 have been fully considered but they are not persuasive. Claim 21 is still withdrawn as discussed above. The restriction of claim 21 was proper as being drawn to a non-elected species based on the claim language of new claim 21 when it was added to the claims.
As discussed above, amended claim 1 is rejected under 112(a) for lack of written description and lack of enablement and under 112(b) for being indefinite, and a prior art rejection of claim 1 and claims depending from claim 1 cannot currently be made due to the scope of claim 1 being indefinite. In the interview on 04/06/2026, Examiners suggested claim language with structural limitations for more clearly defining the claimed pipe in relation to its connection to the primary fuel-oil heat exchanger and to the valve, but that alone will not overcome the 112(a) and 112(b) rejections. Claim 1 needs to be amended with limitations that are supported by the original disclosure.
To clarify after the interview on 06/26/2026 where Applicant did not authorize a proposed examiner’s amendment, upon further review of Applicant’s specification as originally filed and currently amended claim 1 language, as well as the suggested language in the interview summary for the 04/06/2026 interview, a limitation claiming fuel flow without increasing pressure through the pipe is not supported by the original disclosure. Amending with limitations supported by the original disclosure to include additional structural features is suggested.
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.
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/A.J.H./Examiner, Art Unit 3741
/GERALD L SUNG/ Primary Examiner, Art Unit 3741
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