Prosecution Insights
Last updated: April 19, 2026
Application No. 18/008,906

DEVICE FOR FILTERING COOLING AIR OF A TURBOMACHINE TURBINE

Non-Final OA §103§112
Filed
Dec 07, 2022
Examiner
MCKENZIE, THOMAS B
Art Unit
1776
Tech Center
1700 — Chemical & Materials Engineering
Assignee
SAFRAN
OA Round
3 (Non-Final)
57%
Grant Probability
Moderate
3-4
OA Rounds
3y 3m
To Grant
80%
With Interview

Examiner Intelligence

Grants 57% of resolved cases
57%
Career Allow Rate
551 granted / 961 resolved
-7.7% vs TC avg
Strong +23% interview lift
Without
With
+22.9%
Interview Lift
resolved cases with interview
Typical timeline
3y 3m
Avg Prosecution
91 currently pending
Career history
1052
Total Applications
across all art units

Statute-Specific Performance

§101
1.0%
-39.0% vs TC avg
§103
46.5%
+6.5% vs TC avg
§102
17.6%
-22.4% vs TC avg
§112
27.5%
-12.5% vs TC avg
Black line = Tech Center average estimate • Based on career data from 961 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 . Claim Rejections - 35 USC § 112(b) 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 6–8 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 6 recites: 6. The low-pressure turbine according to claim 1, further comprising a protective enclosure forming an external shell of a filtration device. Emphasis added. Claim 6 is indefinite because it is unclear if the “filtration device” is the same as the “device for filtering a cooling airflow.” For the purpose of examination, these devices are the same. Therefore, claim 6 is interpreted to read: 6. The low-pressure turbine according to claim 1, further comprising a protective enclosure forming an external shell of the device for filtering a cooling air flow. Claims 7 and 8 are indefinite because they depend from claim 1. Also, claim 8 recites: 8. The low-pressure turbine according to claim 6, wherein the protective enclosure has an access hatch positioned facing an opening provided at the external shell of the storage tank. Emphasis added. Claim 8 is indefinite because “the storage tank” lacks antecedent basis. For the purpose of examination, claim 8 reads as follows for consistency with claim 6. 8. The low-pressure turbine according to claim 6, wherein the protective enclosure has an access hatch positioned facing an opening provided at the external shell of the device for filtering a cooling air flow 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. 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. Claims 1, 4–7 and 9 are rejected under 35 U.S.C. 103 as being unpatentable over Correia et al., US 2016/0045923 A1. Regarding claim 1, Correia teaches a low pressure (LP) turbine 36 of a gas turbine engine 10, which reads on the claimed “low-pressure turbine of a turbomachine.” See Correia Fig. 1, [0041]. The LP turbine 36 comprises a particle separator 86 for filtering a cooling fluid air flow. Id. at Fig. 2, [0055], [0003]. The particle separator 86 can be the initial separator 250 illustrated in Fig. 14. Id. at Figs. 2, 14, [0054], [0098]. The inertial separator 250 reads on the “device for filtering a cooling air flow.” The inertial separator 250 comprises a body 252 with a geometry configured to centrifuge the cooling air passing through the body 252. See Correia Fig. 14, [0098]. The body 252 reads on the “duct.” The body 252 has at least one particle outlet 262 dimensioned to allow separation of solid particles contained in the cooling air flow being centrifuged. Id. While the reference is silent as to the body 252 having multiple particle outlets 262, it does suggest that multiple outlets 262 can be provided because it says that the body 252 has “at least one” particle outlet 262. Id. Therefore, it would have been obvious for the body 252 to have multiple particle outlets 262, because the reference suggests that the device can be modified in this way, with the inclusion of additional outlets merely representing duplication of parts. See MPEP 2144.04(VI)(B). With this modification, the particle outlets 262 would read on the “openings dimensioned to allow separation of solid particles contained in said cooling air flow to be centrifuged.” Also, the body 252 has a circular helix shape inscribed on a cylinder of revolution with an axis of revolution, as seen in Figs. 14 and 15. PNG media_image1.png 822 953 media_image1.png Greyscale Regarding claim 4, Correia teaches that a particle-laden concentrated stream passes through the at least one outlet 262 into an area outside of the separator 250 where the stream is stored at least temporarily. See Correia Fig. 18, [0098]. This area reads on the “storage tank for storing solid particles separated from said cooling air flow.” PNG media_image2.png 905 1214 media_image2.png Greyscale Regarding claim 5, Correia teaches that the “storage tank” has an “air-porous shell,” which is the wall on the right-hand side (in Fig. 18) which has a hole that allows air to flow through. Regarding claims 6 and 7, Correia teaches a “protective enclosure” forming an external shell of the separator 250, with the “protective enclosure” having openings allowing the interior of the protective enclosure to be placed in fluid communication with the exterior of the protective enclosure, as seen in the annotated figure below. PNG media_image3.png 973 1754 media_image3.png Greyscale Regarding claim 9, Correia teaches a low pressure (LP) turbine 36 of a gas turbine engine 10, which reads on the claimed “low-pressure turbine.” See Correia Fig. 1, [0041]. The low-pressure turbine 36 comprises a system for cooling it. See Correia Fig. 2, [0003], [0055]. The system comprises a bypass conduit 82 for conveying a cooling air flow fluid 80 taken from a high-pressure compressor 26 to a compartment of the low-pressure turbine. Id. at Fig. 18, [0003], [0049], [0052]. The bypass conduit 82 reads on the “utility tube.” The bypass conduit 82 includes an inertial separator 250 for filtering cooling air flow. See Correia Fig. 18, [0098]. The inertial separator 250 reads on the “device for filtering cooling air.” The inertial separator 250 is positioned between an “upstream tube” connected to the high-pressure compressor 26 (the tube that feeds air from the high-pressure compressor 26 to the bypass conduit 82) and an inducer inlet 302 (the “downstream tube” connected to the low-pressure turbine conduit (as the inducer inlet 302 supplies cooling fluid, and the low pressure turbine requires cooling fluid). Id. at [0003], [0096]. The inertial separator 250 comprises a body 252 with a geometry configured to centrifuge the cooling air passing through the body 252. See Correia Fig. 14, [0098]. The body 252 reads on the “duct.” The body 252 has at least one particle outlet 262 dimensioned to allow separation of solid particles contained in the cooling air flow being centrifuged. Id. While the reference is silent as to the body 252 having multiple particle outlets 262, it does suggest that multiple outlets 262 can be provided because it says that the body 252 has “at least one” particle outlet 262. Id. Therefore, it would have been obvious for the body 252 to have multiple particle outlets 262, because the reference suggests that the device can be modified in this way, with the inclusion of additional outlets merely representing duplication of parts. See MPEP 2144.04(VI)(B). With this modification, the particle outlets 262 would read on the “openings dimensioned to allow separation of solid particles contained in said cooling air flow to be centrifuged.” Also, the body 252 has a circular helix shape inscribed on a cylinder of revolution with an axis of revolution, as seen in Figs. 14 and 15. Claims 2 and 3 are rejected under 35 U.S.C. 103 as being unpatentable over Correia et al., US 2016/0045923 A1 in view of Good, US 1,306,003. Regarding claim 2, Correia teaches the limitations of claim 1, as explained above. Correia differs from claim 2 because it is silent as to the body 252 (the “duct”) being a tube with a circular cross-section. But the inertial separator 250 has the helically-shaped body 252 so that relatively heavy dust particles separate from relatively light air due to centrifugal force as dust-laden air spins within the body 252. With this in mind, Good teaches a separator comprising a helically curved pipe 1 that separates relatively heavy liquid from relatively light gas as the gas-liquid mixture flows through the pipe 1 due to centrifugal force. See Good Fig. 1, p. 1, ll. 66–98. The pipe 1 has a circular cross-section, as seen in Fig. 1. PNG media_image4.png 776 755 media_image4.png Greyscale It would have been obvious for the body 252 of Correia to have circular cross-sectional shape, in view of Good, because this would merely be a matter of design choice. See MPEP 2144.04(IV)(B). Regarding claim 3, Correia teaches that the outlets 262 (the “openings”) are provided in a radially outer side of tubular wall 254 of the body 252 (the “duct”) with respect to the axis of revolution. See Correia [0107]. Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Correia et al., US 2016/0045923 A1 in view of Renggli et al., US 2016/0003094 A1. Regarding claim 8, Correia teaches the limitations of claim 6, as explained above. Correia differs from claim 8 because it is silent as to the “protective enclosure” having an access hatch positioned facing an opening provided at the external shell. But the “protective enclosure” is part of the body of a gas turbine engine. With this in mind, Renggli teaches a cowl 130 for a gas turbine engine comprising an access cover 142 facing an opening provided in the cowl 130, which allows access to the interior the cowl 130. See Renggli Fig. 3, [0029]. It would have been obvious to provide an access cover in the “protective enclosure” of Correia to allow access to the interior of the body of the gas turbine engine. Response to Arguments 35 U.S.C. 112(b) Rejections The Examiner withdraws the previous 35 U.S.C. 112(b) rejection of claim 9 in light of the amendments. The Examiner maintains that claim 6 is indefinite for the reasons stated above. 35 U.S.C. 102 & 103 Rejections Applicant’s arguments with respect to the pending claims have been considered but are moot because the new ground of rejection does not rely on any reference applied in the prior rejection of record for any teaching or matter specifically challenged in the argument. 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. Any inquiry concerning this communication or earlier communications from the examiner should be directed to T. BENNETT MCKENZIE whose telephone number is (571)270-5327. The examiner can normally be reached Mon-Thurs 7:30AM-6:00PM. 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, Jennifer Dieterle can be reached at 571-270-7872. 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. T. BENNETT MCKENZIE Primary Examiner Art Unit 1776 /T. BENNETT MCKENZIE/Primary Examiner, Art Unit 1776
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Prosecution Timeline

Dec 07, 2022
Application Filed
Dec 07, 2022
Response after Non-Final Action
Mar 18, 2025
Non-Final Rejection — §103, §112
Jun 04, 2025
Response Filed
Jun 17, 2025
Final Rejection — §103, §112
Aug 19, 2025
Response after Non-Final Action
Sep 08, 2025
Request for Continued Examination
Sep 10, 2025
Response after Non-Final Action
Dec 18, 2025
Non-Final Rejection — §103, §112 (current)

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Study what changed to get past this examiner. Based on 5 most recent grants.

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Prosecution Projections

3-4
Expected OA Rounds
57%
Grant Probability
80%
With Interview (+22.9%)
3y 3m
Median Time to Grant
High
PTA Risk
Based on 961 resolved cases by this examiner. Grant probability derived from career allow rate.

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