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 .
Status of Claims
This action is in response to the claims filed on 07/07/2026. Wherein claims 1, 3-6, 8, and 10 are amended, claims 2 and 9 are cancelled, and claims 11-13 are new. Claims 1, 3-8, and 10-13 are rejected.
Response to Arguments
Applicant’s arguments, see REMARKS, filed 07/07/2026, with respect to the rejection of claims 9 and 10, under 35 USC § 101, have been fully considered and are persuasive. Therefore, the previous rejections under 35 USC § 101 have been withdrawn.
Applicant's arguments with respect to the rejection of claims 1-10, under 35 USC § 103, have been fully considered but they are not persuasive. Therefore, the previous rejections are maintained.
With respect to claim 1, the Applicant argues:
Claim 1 has been amended to include limitations from claims 2-4 and the specification and now requires:
wherein the gaseous fuel and the liquid fuel are supplied in parallel or
alternatively to each other to a combustion chamber of at least one engine of the
aircraft, wherein the aircraft is operated with a positive flow of gaseous fuel during
at least idling, take-off, climbing, cruising and landing operating phases of the
aircraft, the positive flow of gaseous fuel being set at least at a level sufficient for
the idling operating phase
while the liquid fuel flow is varied.
See the present specification at paragraphs [0006]-[0011], [0013], [0026]-[0031] and [0033] and Figs. 1-3.
The Office states (emphasis added):
Speak does not explicitly teach wherein the aircraft is operated at least temporarily with a constant flow of gaseous fuel, while the liquid fuel flow is varied.
However, Epstein discloses dual fuel aircraft system and method for operating the
same and teaches:
wherein the aircraft is operated at least temporarily with a constant
flow of gaseous fuel, while the liquid fuel flow is varied. . . . See at least H [0077]
Here, at the start of the process the system varies the liquid fuel from 0% to 100%
of use while the gaseous fuel flow remains constant at o%.)
In summary, Speak discloses that the various fuel flows maybe tuned
based on the needs of the system. Speak does not explicitly teach that the aircraft
is operated at least temporarily with a constant flow of gaseous fuel, while the
liquid fuel is varied. However, Epstein discloses dual fuel aircraft system and
method for operating the same and teaches that different flight phases may use
different fuels depending on the efficiency of that fuel at that stage. In a scenario
of starting phases of the flight, e.g., engine start, warmup/ground idle, taxi, and
takeoff, the fuel system may use only liquid fuel, e.g., kerosine, during these
phases. This means that the liquid fuel flow is varied from 0%-100% while the
gaseous fuel, e.g., LNG, is maintained at a constant flow of 0%.
Thus, the Office appears to interpret "constant flow of gaseous fuel) as being a flow of 0% gaseous fuel. See the paragraph bridging pages 6-7 of the Action.
Claim 1 has been amended to: 1) remove the "at least temporarily"; 2) require a
constant non-zero flow of gaseous fuel and 3) add a specific definition of the operating
phases for which the positive flow of gaseous fuel is set at least at a level sufficient for
the idling operating phase.
Thus, the combination of Speak and Epstein does not teach, suggest or otherwise
render obvious the required positive flow of gaseous fuel during at least idling, take-off,
climbing, cruising and landing operating phases of the aircraft, the positive flow of
gaseous fuel being set at least at a level sufficient for the idling operating phase, while
the liquid fuel flow is varied.
For the reasons given above, claim 1 is believed to be allowable over the cited art and it is respectfully requested that the rejection of claim 1 be withdrawn.
The Examiner cordially disagrees.
The claims do not currently “require a constant non-zero flow of gaseous fuel”. Instead, the claims require a non-zero flow of gaseous fuel which may be constant or varied. The prior art discloses a varied non-zero flow gaseous fuel during the different flight phases. In other words, the prior claim language was interpreted as a constant flow, i.e., keeping a specific flow rate during the phase. While the current amended claim language is interpreted as a variable flow rate but always some value that is positive, ie., keeping a range of flow rates above zero during the phase.
Speak discloses that the ratio of hydrogen to hydrocarbon can be varied to therefore enable the performance of the propulsion system to be “tuned” as required. (¶ [0084], See also ¶ [0074]-[0082] for how the ratios may be applied) While Epstein discloses “In an embodiment, during selected portions of the operation of the aircraft system 5, the gas turbine engine 101 is capable of generating the propulsive thrust using both the first fuel 11 and the second fuel 12 simultaneously. The proportion of the first fuel and second fuel may be varied between 0% to 100% as appropriate during various stages of the operation of the dual fuel propulsion system 100.” (¶ [0077]) Epstein further teaches that the flight phases include idling, take-off, climbing, cruising, and landing. (See at least Fig. 7)
Therefore, the Examiner does not agree that the amended claims overcome the prior art of record.
The applicant further argues:
Claims 3-7 and 11-13 depend from claim 1 and are allowable for the same reasons as claim 1, as well as for the further limitations contained therein.
For the reasons provided above, the Examiner finds this argument unpersuasive.
The Applicant further argues:
Claims 8 and 10 have been made independent and to include limitations corresponding to claim 1, and are allowable for the same reasons as claim 1.
For the reasons provided above, the Examiner finds this argument unpersuasive.
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.
Claim(s) 1, 3-8, and 10 are rejected under 35 U.S.C. 103 as being unpatentable over Speak et al. (Us 2023/0340915 A1, “Speak”) in view of Epstein et al. (US 2013/0186059 A1, “Epstein”)
Regarding claims 1, 8, and 10, Speak discloses a propulsion system and teaches:
A method for operating an aircraft with a gaseous fuel (According to the present disclosure there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows. Accordingly, there may be provided a propulsion system (300) for an aircraft (10) comprising: a first fuel reservoir (100) configured for storing hydrogen (H2-1) – See at least ¶ [0007]-[0008]; Examiner notes that the liquid H2-1 is converted to a gas by hydrogen pilot burner. The hydrogen pilot burner has its own reservoir which contains hydrogen gas (H2-2) – See at least ¶ [0009]-[0010]) and a liquid fuel (a second fuel reservoir (200) configured for storing a hydrocarbon fuel (HC) – See at least ¶ [0008] Examiner notes that examples of hydrocarbon fuels are kerosene or sustainable aviation fuels – See at least ¶ [0072] and [0081]) wherein the gaseous fuel and the liquid fuel are supplied in parallel or alternatively to each other (The dual fuel main burner (520) may comprise a plurality of outlets (524, 528) which surround the hydrogen pilot burner (510). A first subset (528) of dual fuel main burner outlets (524) may be in flow communication with the first fuel reservoir (100) via a first flow passage (550); and a second subset (530) of the dual fuel main burner outlets (524) are in flow communication with the second fuel reservoir (200) via a second flow passage (552); the first flow passage (550) and second flow passage (552) being fluidly isolated from one another – See at least ¶ [0013]-[0023]) to a combustion chamber of at least one engine of the aircraft, (The gas turbine engine (400) may further comprise a combustor (700) – See at least ¶ [0024]) []
Speak does not explicitly teach wherein the aircraft is operated at least temporarily with a constant flow of gaseous fuel, while the liquid fuel flow is varied. However, Epstein discloses dual fuel aircraft system and method for operating the same and teaches:
wherein the aircraft is operated with a positive flow of gaseous fuel during at least idling, take-off, climbing, cruising, and landing operating phases of the aircraft, the positive flow of gaseous fuel being set at least at a level sufficient for the idling operating phase, while the liquid fuel flow is varied. (An exemplary method of operation of the aircraft system 5 using a dual fuel propulsion system 100 according to an embodiment of the present invention is described as follows with respect to an exemplary flight mission profile shown schematically in FIG. 7. The exemplary flight mission profile shown schematically in FIG. 7 shows the Engine power setting during various portions of the flight mission identified by the letter labels A-B-C-D-E-...-X-Y etc. For example, A-B represents the start, B-C shows ground-idle, G-H shows take-off, T-L and O-P show cruise, etc. During operation of the aircraft system 5 (See exemplary flight pro file 120 in FIG. 7), the gas turbine engine 101 in the propulsion system 100 may use, for example, the first fuel 11 during a first selected portion of operation of propulsion system, Such as for example, during take-off. The propulsion system 100 may use the second fuel 12, such as, for example, LNG, during a second selected portion of operation of propulsion system such as during cruise – See at least ¶ [0077])
In summary, Speak discloses that the various fuel flows may be tuned based on the needs of the system. Speak does not explicitly teach that t wherein the aircraft is operated with a positive flow of gaseous fuel during at least idling, take-off, climbing, cruising, and landing operating phases of the aircraft, the positive flow of gaseous fuel being set at least at a level sufficient for the idling operating phase, while the liquid fuel flow is varied. However, Epstein discloses dual fuel aircraft system and method for operating the same and teaches that different flight phases may use different fuels depending on the efficiency of that fuel at that stage. This includes a varied combination of both fuel types during the various phases.
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak to provide for dual fuel aircraft system and method for operating the same, as taught in Epstein, because the step of varying the proportion of the first fuel 12 and the second fuel 13 during different portions of the flight profile 120 may be used to advantage to operate the aircraft system in an economic and efficient manner. (At Epstein ¶ [0080])
Regarding claim 3, Speak does not explicitly teach, but Epstein further teaches:
wherein the aircraft is operated with the positive flow of gaseous fuel from the operating phase of idling, immediately after an operating phase of ignition until an operating phase of off at an end of the entire operating period of a flight mission or from an operating phase of taxiing before the operating phase of take-off until the operating phase of taxiing after the operating phase of landing. (An exemplary method of operation of the aircraft system 5 using a dual fuel propulsion system 100 according to an embodiment of the present invention is described as follows with respect to an exemplary flight mission profile shown schematically in FIG. 7. The exemplary flight mission profile shown schematically in FIG. 7 shows the Engine power setting during various portions of the flight mission identified by the letter labels A-B-C-D-E-...-X-Y etc. For example, A-B represents the start, B-C shows ground-idle, G-H shows take-off, T-L and O-P show cruise, etc. During operation of the aircraft system 5 (See exemplary flight pro file 120 in FIG. 7), the gas turbine engine 101 in the propulsion system 100 may use, for example, the first fuel 11 during a first selected portion of operation of propulsion system, Such as for example, during take-off. The propulsion system 100 may use the second fuel 12, such as, for example, LNG, during a second selected portion of operation of propulsion system such as during cruise – See at least ¶ [0077] and Fig. 7)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak to provide for dual fuel aircraft system and method for operating the same, as taught in Epstein, because the step of varying the proportion of the first fuel 12 and the second fuel 13 during different portions of the flight profile 120 may be used to advantage to operate the aircraft system in an economic and efficient manner. (At Epstein ¶ [0080])
Regarding claim 4, Speak does not explicitly teach, but Epstein further teaches:
wherein an amount of flow of the level sufficient of gaseous fuel corresponds at maximum, a required flow of gaseous fuel for operating the engine while the aircraft is taxiing. (An exemplary method of operation of the aircraft system 5 using a dual fuel propulsion system 100 according to an embodiment of the present invention is described as follows with respect to an exemplary flight mission profile shown schematically in FIG. 7. The exemplary flight mission profile shown schematically in FIG. 7 shows the Engine power setting during various portions of the flight mission identified by the letter labels A-B-C-D-E-...-X-Y etc. For example, A-B represents the start, B-C shows ground-idle, G-H shows take-off, T-L and O-P show cruise, etc. During operation of the aircraft system 5 (See exemplary flight pro file 120 in FIG. 7), the gas turbine engine 101 in the propulsion system 100 may use, for example, the first fuel 11 during a first selected portion of operation of propulsion system, Such as for example, during take-off. The propulsion system 100 may use the second fuel 12, such as, for example, LNG, during a second selected portion of operation of propulsion system such as during cruise – See at least ¶ [0077] and Fig. 7; Here, the required flow of the gaseous fuel is 0% and it is constant.)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak to provide for dual fuel aircraft system and method for operating the same, as taught in Epstein, because the step of varying the proportion of the first fuel 12 and the second fuel 13 during different portions of the flight profile 120 may be used to advantage to operate the aircraft system in an economic and efficient manner. (At Epstein ¶ [0080])
Regarding claim 5, Speak further teaches:
wherein the at least one engine is ignited exclusively with the gaseous fuel. (In a first mode of operation, as shown in FIG. 3, the first flow control valve 512 is open, the second flow control valve 522 is closed and the third flow control valve 532 is closed such that only hydrogen is delivered to the pilot burner 510. The first mode of operation may correspond to a gas turbine engine 400 start, idle and/or low-power condition.– See at least ¶ [0056])
Regarding claim 6, Speak does not explicitly teach, but Epstein further teaches:
wherein the liquid fuel is switched on for operating phases in which the power of the at least one engine exceeds a power in the operating phase of idling and/or in the operating phase of taxiing, the engine being operated in parallel with the gaseous fuel and the liquid fuel. (An exemplary method of operation of the aircraft system 5 using a dual fuel propulsion system 100 according to an embodiment of the present invention is described as follows with respect to an exemplary flight mission profile shown schematically in FIG. 7. The exemplary flight mission profile shown schematically in FIG. 7 shows the Engine power setting during various portions of the flight mission identified by the letter labels A-B-C-D-E-...-X-Y etc. For example, A-B represents the start, B-C shows ground-idle, G-H shows take-off, T-L and O-P show cruise, etc. During operation of the aircraft system 5 (See exemplary flight pro file 120 in FIG. 7), the gas turbine engine 101 in the propulsion system 100 may use, for example, the first fuel 11 during a first selected portion of operation of propulsion system, Such as for example, during take-off. The propulsion system 100 may use the second fuel 12, such as, for example, LNG, during a second selected portion of operation of propulsion system such as during cruise. In an embodiment, during selected portions of the operation of the aircraft system 5, the gas turbine engine 101 is capable of generating the propulsive thrust using both the first fuel 11 and the second fuel 12 simultaneously. The proportion of the first fuel and second fuel may be varied between 0% to 100% as appropriate during various stages of the operation of the dual fuel propulsion system 100 – See at least ¶ [0077] and Fig. 7)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak to provide for dual fuel aircraft system and method for operating the same, as taught in Epstein, because the step of varying the proportion of the first fuel 12 and the second fuel 13 during different portions of the flight profile 120 may be used to advantage to operate the aircraft system in an economic and efficient manner. (At Epstein ¶ [0080])
Regarding claim 7, Speak further teaches:
wherein the gaseous fuel is stored and/or provided in gaseous or liquid form, (The first fuel reservoir (100) may be a low temperature and low-pressure reservoir for storing liquid hydrogen. The propulsion system may further comprise a third fuel reservoir (800) configured for storing pressurized
hydrogen gas (H2-2) – See at least ¶ [0009]) the gaseous fuel when stored and/or provided in liquid form being evaporated before being supplied to the combustion chamber. (The heat exchanger 110 may be in thermal communication with a heat source. In some examples the heat source may be the engine 400. Hence some of the heat generated by the engine 400 may be transferred to the liquid hydrogen as it travels between the first reservoir 102 the fuel injection unit 500 – See at least ¶ [0036] and [0040])
Claim(s) 11-13 are rejected under 35 U.S.C. 103 as being unpatentable over Speak in view of Epstein, as applied to claim 1, and in further view of Meeuwissen et al. (US 2012/0247116 A1, “Meeuwissen”).
Regarding claim 11, Epstein further teaches:
wherein the positive flow of gaseous fuel is [tuned] during the idling, take-off, climbing, cruising and landing operating phases of the aircraft. (Fig. 7 shows the flight phases of idling, take-off, climbing, cruising, and landing.)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak to provide for dual fuel aircraft system and method for operating the same, as taught in Epstein, because the step of varying the proportion of the first fuel 12 and the second fuel 13 during different portions of the flight profile 120 may be used to advantage to operate the aircraft system in an economic and efficient manner. (At Epstein ¶ [0080])
The combination of Speak and Epstein does not explicitly teach wherein the positive flow of gaseous fuel is substantially constant during the idling, take-off, climbing, cruising and landing operating phases of the aircraft. However, Meeuwissen discloses method for switch over a gas turbine burner operation from liquid to gas fuel and vice-versa and teaches:
wherein the positive flow of gaseous fuel is substantially constant during the [operation] of the aircraft. (according to the method, while the liquid fuel 21 and the premix gas fuel 22 are regulated to Switch over from liquid fuel to gas fuel operation or Vice-versa, the pilot gas fuel 23 is controlled at a substantially constant flow rate (i.e. Small changes of the pilot gas fuel flow rate are possible, but they do not affect the operation of the burner) – See at least ¶ [0032])
In summary, Epstein teaches operating the gaseous fuel during each flight phase of aircraft operation. Epstein further teaches that the flight phases include idling, take-off, climbing, cruising, and landing operations. The combination of Speak and Epstein does not explicitly teach that the flow of gaseous fuel is substantially constant during these phases. However, Meeuwissen teaches maintaining a constant flow of gaseous fuel the while the aircraft is operating.
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak and Epstein to provide for the method for switching over a gas turbine burner operation from liquid to gas fuel and vice-versa, as taught in Meeuwissen, to control flame stability. (At Meeuwissen ¶ [0034])
Regarding claim 12, Epstein further teaches:
wherein the positive flow of gaseous fuel is [tuned] during the idling, take-off, climbing, cruising, and landing operating phases of the aircraft, and also during a taxiing operating phase of the aircraft. (Fig. 7 shows the flight phases of taxiing, idling, take-off, climbing, cruising, and landing.)
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak to provide for dual fuel aircraft system and method for operating the same, as taught in Epstein, because the step of varying the proportion of the first fuel 12 and the second fuel 13 during different portions of the flight profile 120 may be used to advantage to operate the aircraft system in an economic and efficient manner. (At Epstein ¶ [0080])
The combination of Speak and Epstein does not explicitly teach, but Meeuwissen further teaches:
wherein the positive flow of gaseous fuel is substantially constant during the [operation] of the aircraft. (according to the method, while the liquid fuel 21 and the premix gas fuel 22 are regulated to Switch over from liquid fuel to gas fuel operation or Vice-versa, the pilot gas fuel 23 is controlled at a substantially constant flow rate (i.e. Small changes of the pilot gas fuel flow rate are possible, but they do not affect the operation of the burner) – See at least ¶ [0032])
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak and Epstein to provide for the method for switching over a gas turbine burner operation from liquid to gas fuel and vice-versa, as taught in Meeuwissen, to control flame stability. (At Meeuwissen ¶ [0034])
Regarding claim 13, Meeuwissen further teaches:
wherein the positive flow of gaseous fuel is substantially constant over substantially an entire operating time of the aircraft. (according to the method, while the liquid fuel 21 and the premix gas fuel 22 are regulated to Switch over from liquid fuel to gas fuel operation or Vice-versa, the pilot gas fuel 23 is controlled at a substantially constant flow rate (i.e. Small changes of the pilot gas fuel flow rate are possible, but they do not affect the operation of the burner) – See at least ¶ [0032])
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the instant application to have modified the propulsion system of Speak and Epstein to provide for the method for switching over a gas turbine burner operation from liquid to gas fuel and vice-versa, as taught in Meeuwissen, to control flame stability. (At Meeuwissen ¶ [0034])
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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/C.L.C./Examiner, Art Unit 3662
/ANISS CHAD/Supervisory Patent Examiner, Art Unit 3662
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