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 .
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and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114.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 3/20/2026 has been entered.
Claim Objections
Claims 1 and 8 are objected to because of the following informalities:
Claim 1 recites “the aircraft” in line 13 and should recite “an aircraft”.
Claim 8 recites “the aircraft” in line 17 and should recite “an aircraft”.
Claim 8 recites “compressor the auxiliary power unit” in line 20 and should recite “compressor, the auxiliary power unit”.
Claim 8 recites “an aircraft” in line 21 and should recite “the aircraft”.
Appropriate correction is required.
Claim Rejections - 35 USC § 102
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 the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(2) the claimed invention was described in a patent issued under section 151, or in an application for patent published or deemed published under section 122(b), in which the patent or application, as the case may be, names another inventor and was effectively filed before the effective filing date of the claimed invention.
Claims 1, 3-4, 7-11, 14-16 and 19 are rejected under 35 U.S.C. 102(a)(2) as being clearly anticipated by Foutch et al. (US 2015/0275758).
Regarding claim 1, Foutch discloses an auxiliary power unit air bleed system (Figure 3, 202) comprising:
an auxiliary power unit compressor (208) having an auxiliary power unit bleed air discharge line (236, 244, 302 and 272);
an expansion valve (262) fluidly coupled to the auxiliary power unit bleed air discharge line (Figure 3), wherein the expansion valve is configured to reduce a pressure of auxiliary power unit bleed air flowing through the auxiliary power unit bleed air discharge line and reduce a temperature of the auxiliary power unit bleed air (paragraph 36 describes valve 262 as a pressure regulating valve, and when the pressure is reduced in a constant volume system the temperature is also reduced), the expansion valve fluidly coupled to a main gas turbine engine (Figure 1 shows 2 gas turbine engines 102, one is the auxiliary power unit and the other is the main gas turbine engine. Paragraph 26 describes the two engines as having a common bleed system and paragraph 29 describes the flow from expansion valve 262 going to an engine anti-icing system, i.e. going to the main gas turbine engine anti-icing system), the main gas turbine engine configured to provide propulsion for the aircraft (paragraph 28);
a controller (293) in operative communication with the expansion valve (Figure 3), the controller configured to control operation of at least the expansion valve (paragraph 47); and
an anti-surge valve (291) fluidly coupled to the auxiliary power unit bleed air discharge line downstream from the auxiliary power unit compressor and parallel with the expansion valve (Figure 3), the anti-surge valve fluidly coupled directly with the expansion valve along the auxiliary power unit bleed air discharge line (Examiner notes that the original disclosure does not explicitly state that the two valves are “coupled directly”; however the figures show that the auxiliary power unit bleed air discharge line splits into two lines with one of the valves on each split line. This limitation is therefore understood to mean that each of the valves is on a respective line that is connected to the other line. Figure 3 shows the auxiliary power unit bleed air discharge line 236 splits at 302 into line 272 which contains anti-surge valve 291 and line 244 which contains expansion valve 262) downstream from the auxiliary power unit compressor (Figure 3 shows the auxiliary power unit bleed air discharge line and the valves are each downstream of the compressor 210); the anti-surge valve fluidly coupled to an auxiliary power unit turbine exhaust line (paragraph 45 describes the bleed air dumped by the anti-surge valve 291 into the turbine and thus into the turbine exhaust line of the auxiliary power unit).
Regarding claim 3, Foutch discloses at least one sensor (298a) in operative communication with the auxiliary power unit bleed air discharge line and the controller (Figure 3 and paragraph 47).
Regarding claim 4, Foutch discloses wherein the at least one sensor is configured as a pressure sensor or a temperature sensor (paragraph 47 describes sensor 298a as a pressure sensor).
Regarding claim 7, Foutch discloses wherein the expansion valve is configured to cool the auxiliary power unit bleed air (paragraph 36 describes valve 262 as a pressure regulating valve, and when the pressure is reduced in a constant volume system the temperature is also reduced) enabling the auxiliary power unit compressor to operate at a compression ratio from 4.5 to 10 (intended use, the system is structurally capable of operating at a compression ratio from 4.5 to 10).
Regarding claim 8, Foutch discloses a gas turbine engine with an auxiliary power unit air bleed system (Figure 3, 202) comprising:
an auxiliary power unit main shaft (216) coupled with an auxiliary power unit compressor (210) and an auxiliary power unit turbine (220), wherein the auxiliary power unit main shaft is a single shaft (Figure 3 and paragraph 27 describe shaft 216 as a single shaft);
an auxiliary power unit combustor (214) fluidly coupled between the auxiliary power unit compressor and the auxiliary power unit turbine (Figure 3);
an auxiliary power unit gearbox (290) directly coupled to the auxiliary power unit main shaft (Figure 2 and paragraph 41 describes the gearbox 290 as directly coupled to the shaft 216);
an auxiliary power unit electrical generator (paragraph 41) in operative communication with the auxiliary power unit gearbox (paragraph 41 describes an electrical generator operatively connected to the gearbox), the auxiliary power unit electrical generator electrically connected with a main gas turbine engine (Figure 1 shows 2 gas turbine engines 102, one is the auxiliary power unit and the other is the main gas turbine engine. Paragraph 49 describes the control system 293 as part of a main control system 299 of the aircraft, which necessarily sends electrical signals to and from both the auxiliary power unit, and thus the generator, and the main gas turbine engine 102.), the main gas turbine engine configured to provide propulsion for the aircraft (paragraph 28);
an auxiliary power unit bleed air discharge line (236, 244, 302 and 272) fluidly coupled downstream of the auxiliary power unit compressor (Figure 3 shows the line receives airflow from compressor 210 and is located downstream of compressor 210) the auxiliary power unit bleed air discharge line fluidly coupled with an aircraft and the main gas turbine engine (Figure 1 shows 2 gas turbine engines 102, one is the auxiliary power unit and the other is the main gas turbine engine. Paragraph 26 describes the two engines as having a common bleed system and paragraph 29 describes the flow from expansion valve 262 going to an engine anti-icing system, i.e. going to the main gas turbine engine anti-icing system);
an expansion valve (262) fluidly coupled to the auxiliary power unit bleed air discharge line (Figure 3), wherein the expansion valve is configured to reduce a pressure of auxiliary power unit bleed air flowing through the auxiliary power unit bleed air discharge line and reduce a temperature of the auxiliary power unit bleed air (paragraph 36 describes valve 262 as a pressure regulating valve, and when the pressure is reduced in a constant volume system the temperature is also reduced); and
an anti-surge valve (291) fluidly coupled to the auxiliary power unit bleed air discharge line downstream from the auxiliary power unit compressor and parallel with the expansion valve (Figure 3), the anti-surge valve fluidly coupled directly with the expansion valve along the auxiliary power unit bleed air discharge line (Examiner notes that the original disclosure does not explicitly state that the two valves are “coupled directly”; however the figures show that the auxiliary power unit bleed air discharge line splits into two lines with one of the valves on each split line. This limitation is therefore understood to mean that each of the valves is on a respective line that is connected to the other line. Figure 3 shows the auxiliary power unit bleed air discharge line 236 splits at 302 into line 272 which contains anti-surge valve 291 and line 244 which contains expansion valve 262) downstream from the auxiliary power unit compressor (Figure 3 shows the auxiliary power unit bleed air discharge line and the valves are each downstream of the compressor 210), the anti-surge valve fluidly coupled with a auxiliary power unit turbine exhaust line (paragraph 45 describes the bleed air dumped by the anti-surge valve 291 into the turbine and thus into the turbine exhaust line of the auxiliary power unit).
Regarding claim 9, Foutch discloses a controller (293) in operative communication with the expansion valve (Figure 3), the controller configured to control operation of at least the expansion valve (paragraph 47).
Regarding claim 10, Foutch discloses at least one sensor (298a) in operative communication with the auxiliary power unit bleed air discharge line and the controller (Figure 3 and paragraph 47).
Regarding claim 11, Foutch discloses wherein the at least one sensor is configured as a pressure sensor or a temperature sensor (paragraph 47 describes sensor 298a as a pressure sensor).
Regarding claim 14, Foutch discloses a process for configuring an auxiliary power unit air bleed system (Figure 3, 202) comprising:
fluidly coupling an auxiliary power unit compressor (208) having an auxiliary power unit bleed air discharge line (236, 244, 302 and 272); and
fluidly coupling an expansion valve (262) fluidly coupled to the auxiliary power unit bleed air discharge line (Figure 3);
fluidly coupling the expansion valve to a main gas turbine engine (Figure 1 shows 2 gas turbine engines 102, one is the auxiliary power unit and the other is the main gas turbine engine. Paragraph 26 describes the two engines as having a common bleed system and paragraph 29 describes the flow from expansion valve 262 going to an engine anti-icing system, i.e. going to the main gas turbine engine anti-icing system);
configuring the main gas turbine engine to provide propulsion to an aircraft (paragraph 28);
coupling an anti-surge valve (291) to the auxiliary power unit bleed air discharge line downstream from the compressor and parallel with the expansion valve (Figure 3), the anti-surge valve fluidly coupled directly with the expansion valve along the auxiliary power unit bleed air discharge line (Examiner notes that the original disclosure does not explicitly state that the two valves are “coupled directly”; however the figures show that the auxiliary power unit bleed air discharge line splits into two lines with one of the valves on each split line. This limitation is therefore understood to mean that each of the valves is on a respective line that is connected to the other line. Figure 3 shows the auxiliary power unit bleed air discharge line 236 splits at 302 into line 272 which contains anti-surge valve 291 and line 244 which contains expansion valve 262) downstream from the auxiliary power unit compressor (Figure 3 shows the auxiliary power unit bleed air discharge line and the valves are each downstream of the compressor 210);
fluidly coupling the anti-surge valve to an auxiliary power unit turbine exhaust line (paragraph 45 describes the bleed air dumped by the anti-surge valve 291 into the turbine and thus into the turbine exhaust line of the auxiliary power unit);
reducing a pressure of auxiliary power unit bleed air flowing through the auxiliary power unit bleed air discharge line with the expansion valve (This claim is directed to a process of configuring, not a method of using, the article; therefore this limitation is intended use. Paragraph 36 describes valve 262 as a pressure regulating valve); and
reducing a temperature of the auxiliary power unit bleed air flowing through the auxiliary power unit bleed air discharge line with the expansion valve (This claim is directed to a process of configuring, not a method of using, the article; therefore this limitation is intended use. Paragraph 36 describes valve 262 as a pressure regulating valve, and when the pressure is reduced in a constant volume system the temperature is also reduced).
Regarding claim 15, Foutch discloses coupling a controller (293) in operative communication with the expansion valve (Figure 3), the controller configured to control operation of at least the expansion valve (paragraph 47).
Regarding claim 16, Foutch discloses coupling at least one sensor (298a) in operative communication with the auxiliary power unit bleed air discharge line and the controller (Figure 3 and paragraph 47) , wherein the at least one sensor is configured as a pressure sensor or a temperature sensor (paragraph 47 describes sensor 298a as a pressure sensor).
Regarding claim 19, Foutch discloses configuring the expansion valve to cool the auxiliary power unit bleed air (paragraph 36 describes valve 262 as a pressure regulating valve, and when the pressure is reduced in a constant volume system the temperature is also reduced); and
enabling the auxiliary power unit compressor to operate at a compression ratio from 4.5 to 10 (This claim is directed to a process of configuring, not a method of using, the article; therefore this limitation is intended use. The system is structurally capable of operating at a compression ratio from 4.5 to 10).
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.
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.
Claim 20 is rejected under 35 U.S.C. 103 as being unpatentable over Foutch et al. (US 2015/0275758) in view of Spraker et al. (US 4,149,371).
Regarding claim 20, Foutch discloses all the essential features of the claimed invention as described above except configuring the expansion valve as a fixed diameter valve; and configuring the expansion valve as a passive valve.
Spraker teaches configuring the expansion valve as a fixed diameter valve (col. 2, ll. 35-38 describe valve 26 is a poppet valve, i.e. fixed diameter valve); and configuring the expansion valve as a passive valve (col. 2, ll. 35-38 describe valve 26 is a pressure actuated poppet valve, i.e. the valve opens when the fluid reaches a particular pressure passively).
Therefore it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify Foutch’s invention to include configuring the expansion valve as a fixed diameter valve; and configuring the expansion valve as a passive valve in order to provide bleed air flow at an appropriate pressure without adding additional complication to the system as suggested and taught by Spraker in col. 1, ll. 58-63.
Response to Arguments
Applicant's arguments filed 3/20/2026 have been fully considered but they are not persuasive.
Applicant argues on pages 8-13 of the Remarks “There is no teaching or suggestion that the Foutch engine 200 is anything but a main gas turbine engine of an aircraft and cannot be confused to be an auxiliary power unit of the aircraft. The auxiliary power unit of an aircraft is not a main gas turbine engine of an aircraft, this is well known”. Applicant appears to be arguing that there is a specific definition of an auxiliary power unit that differentiates it from the gas turbine engine described by Foutch; however, Applicant has not given any evidence to this and merely asserts that a person having ordinary skill in the art would know the difference. Applicant’s admitted prior art, Szillat et al. (US Patent 11,279,490), discloses that an auxiliary power unit is an engine, such as a gas turbine engine in col. 1, ll. 12-13. Therefore, this argument is not persuasive.
Applicant argues on page 14 that “The claimed auxiliary power unit supports the claimed main gas turbine engine, the main gas turbine engine provides propulsion to the aircraft. The auxiliary power unit does not provide propulsion to the aircraft.” As described in the rejection above, Foutch teaches a main gas turbine engine that provides propulsion to the aircraft; however, the claims do not require that the auxiliary power unit does not provide propulsion to the aircraft. Therefore this argument is moot.
Applicant argues on pages 14-15 that the two valves are not plumbed to the same line. Figure 3 clearly shows that each of valves 291 and 262 are on respective split lines from the main bleed line 236. Additionally, the new limitations regarding the fluid connections with the two valves are described above. Therefore this argument is not persuasive.
Applicant argues on pages 15-17 “The Foutch refence discloses a completely different structure than the claimed an auxiliary power unit main shaft coupled with an auxiliary power unit compressor and an auxiliary power unit turbine. There is only a single auxiliary power unit main shaft claimed, not multiple shafts as disclosed in Foutch. The auxiliar power unit compressor is connected to the same auxiliary power unit main shaft as the auxiliary power unit turbine.” Foutch teaches a single shaft 216 connecting the auxiliary power unit compressor 210 and the auxiliary power unit turbine 220, so this argument is not persuasive.
Applicant argues on pages 17-18 that Foutch’s gearbox 290 is not directly coupled to the auxiliary power unit main shaft 216. Foutch describes in paragraph 41 “the second gear 290 may be operatively coupled to and driven by the LPC drive shaft 216”. Therefore this argument is not persuasive.
Conclusion
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Katheryn Malatek whose telephone number is (571)272-5689. The examiner can normally be reached Monday - Thursday, 9 am - 6 pm.
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.
/KATHERYN A MALATEK/Primary Examiner, Art Unit 3741
Prosecution Insights