Sankrithi, Mithra M.K.V. et al.

Patent Trials and Appeals Board

Jan 2, 2020

13897452 - (D) (P.T.A.B. Jan. 2, 2020)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
13/897,452 05/20/2013 Mithra M.K.V. Sankrithi 2-129(12-1655) 5178
121171 7590 01/02/2020
McDonnell Boehnen Hulbert & Berghoff LLP/BOEING
300 South Wacker Drive,
Suite 3100
Chicago, IL 60606
EXAMINER
HUTCHENS, CHRISTOPHER D.
ART UNIT PAPER NUMBER
3647
MAIL DATE DELIVERY MODE
01/02/2020 PAPER
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte MITHRA M.K.V. SANKRITHI, ARVIN SHAJANIAN,
SERGEY D. BARMICHEV, VICTOR KEN STUHR,
JOSHUA M. KUSNITZ, and ISMAIL ROBBANA
___________

Appeal 2019-004286
Application 13/897,452
Technology Center 3600
____________

Before JAMES P. CALVE, ANNETTE R. REIMERS, and
MICHAEL L. WOODS, Administrative Patent Judges.

REIMERS, Administrative Patent Judge.

DECISION ON APPEAL

STATEMENT OF THE CASE
Appellant1 appeals under 35 U.S.C. § 134(a) from the Examiner’s
decision to reject under 35 U.S.C. § 103 claims 1–4, 6–18, 20, and 22 as
unpatentable over Epstein (US 2014/0026597 A1, published Jan. 30, 2014),
Lee (US 2005/0051666 A1, published Mar. 10, 2005), and Tichborne (US
2012/0248251 A1, published Oct. 4, 2012). Claims 5, 19, and 21 have been
canceled. We have jurisdiction under 35 U.S.C. § 6(b).

1 We use the word “Appellant” to refer to “applicant” as defined in 37 C.F.R.
§ 1.42. Appellant identifies the real party in interest as “The Boeing
Company.” Appeal Brief (“Appeal Br.”) 1, filed Nov. 30, 2018.

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Application 13/897,452

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We REVERSE.

CLAIMED SUBJECT MATTER
The claimed subject matter “relate[s] to aircraft fuel systems.” Spec.
¶ 1, Figs. 6, 15. Claims 1, 15, and 20 are independent.
Claim 1 is illustrative of the claimed subject matter and recites:
1. A hybrid fuel airplane comprising:
an airplane body conformed to an outer mold line;
an airplane wing coupled to the airplane body and operable
to generate aerodynamic lift;
an airplane propulsor operable to generate thrust; and
an airplane fuel system operable to carry fuel usable by the
airplane propulsor and comprising:
at least one cryogenic fuel tank including (i) a first portion
located behind an aft pressure bulkhead of the airplane body,
forward of an aft tailcone, and below a vertical tail portion of the
airplane body, and (ii) a second portion located in the vertical tail
portion of the airplane body behind the aft pressure bulkhead,
wherein the first portion of the at least one cryogenic fuel tank
and the second portion of the at least one cryogenic fuel tank
comprise different portions of a single cryogenic fuel tank,
wherein the entirety of the at least one cryogenic fuel tank is
located behind the aft pressure bulkhead of the airplane body,
and wherein the at least one cryogenic fuel tank is in direct fluid
communication with the airplane propulsor; and
a jet fuel tank operable to carry jet fuel and located in the
airplane wing;
wherein the at least one cryogenic fuel tank comprises a
cooling system to maintain the cryogenic fuel contained therein
at a sufficiently low temperature.

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Application 13/897,452

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ANALYSIS
Independent claim 1 is directed to a hybrid fuel airplane including an
airplane body with an aft pressure bulkhead and an airplane fuel system
having at least one cryogenic fuel tank, “wherein the entirety of the at least
one cryogenic fuel tank is located behind the aft pressure bulkhead of the
airplane body.” Appeal Br. 2 (Claims App.).2
The Examiner finds that Epstein discloses the hybrid fuel airplane of
claim 1 including at least one cryogenic fuel tank 123. Final Act. 2–33. The
Examiner also finds that Epstein does not disclose, among other things, that
“the entirety of the at least one cryogenic fuel tank is located behind the aft
pressure bulkhead of the airplane body.” Id. at 3. The Examiner finds that
“Lee teaches an aircraft with a plurality of fuel tanks (202) (fig. 2A) having
a first portion (214) in the empennage, which is understood to be located
behind an aft pressure bulkhead.” Id. The Examiner reasons that it would
have been obvious to a skilled artisan “to have modified Epstein to include
the teachings of Lee to have the tank located in an aircraft empennage
section, since Epstein states the tank (123) may be located in an aft portion
of the fuselage, and doing so would provide space for components forward
of the empennage.” Id.4
Appellant contends that “fuel tanks 214, 216 of Lee are not shown to
be positioned [‘]behind an aft pressure bulkhead of the airplane’ as recited in

2 Claims Appendix (“Claims App.”), filed Jan. 3, 2019.
3 Final Office Action (“Final Act.”), dated May 25, 2018.
4 In the Answer, the Examiner clarifies that the teachings of Tichborne are
not relied upon for disclosing “the entirety of the at least one cryogenic fuel
tank [being] located behind the aft pressure bulkhead of the airplane body.”
Examiner’s Answer (“Ans.”) 5, dated Mar. 15, 2019.
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Application 13/897,452

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claim 1. In fact, the disclosure of Lee does not mention an aft pressure
bulkhead at all.” Reply Br. 45; see also Appeal Br. 5–9. Appellant further
contends that “[t]he Examiner submits that the aft fuselage tank 214 is
located in the empennage. However, Lee does not make this assertion.”
Reply Br. 4. Instead, according to Appellant, “Lee states that ‘[t]he aft body
fuel tank 214 is located between the main landing gear wheel well and the
[Auxiliary Power Unit (APU)]’” and “Lee makes no mention of an aft
pressure bulkhead with respect to the location of the fuel tanks 214, 216.”
Id. (citing Lee ¶ 47).
Appellant has the better position here. Lee discloses that “[t]he
illustrative aircraft has an empennage 114 in the form of an inverted V-tail
that includes a vertical stabilizer 120 and inverted stabilizers 121” and that
“[t]he empennage 114 includes a tail structure section 502, a vertical
stabilizer to inverted stabilizer joint section 504, and an inverted stabilizer to
nacelle joint section 506.” Lee ¶¶ 36, 77 (both emphasis omitted), Figs. 1A,
5A. There is no discussion in Lee of an “aft pressure bulkhead” let alone
that empennage 114 is located “behind an aft pressure bulkhead.” See Final
Act. 3; see also Reply Br. 4; Lee, generally. Further, as correctly pointed
out by Appellant, Lee discloses that “aft body fuel tank 214 is located
between the main landing gear wheel well and the APU.” Reply Br. 4; see
also Lee ¶ 47 (emphasis omitted).
Although Epstein discloses that fuel tank 123 “may be located in an
aft portion of the fuselage of the aircraft system, such as for example shown
schematically in [Figure 1]” (see Epstein ¶ 20 (emphasis added)), there is no

5 Reply Brief (“Reply Br.”), filed May 10, 2019.
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Application 13/897,452

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discussion in Epstein of fuel tank 123 being located “behind the aft pressure
bulkhead,” as claimed. See Appeal Br. 5–6; see also Reply Br. 4; Epstein,
generally. Moreover, the Examiner does not establish that Epstein’s fuel
tank 123 is necessarily located behind an aft pressure bulkhead. See Final
Act. 2–3; see also Ans. 3. In fact, the Examiner acknowledges in the Final
Office Action that Epstein fails to disclose that the entirety of fuel tank 123
is located behind the aft pressure bulkhead of the airplane body and relies on
Lee for this teaching. See Final Act. 3. For these reasons, the Examiner
does not establish by a preponderance of the evidence that the combined
teachings of Epstein and Lee disclose that the entirety of the at least one
cryogenic fuel tank is structurally located “behind the aft pressure bulkhead
of the airplane body,” as set forth in claim 1. Final Act. 2–3; see also Ans.
3; Reply Br. 4; Appeal Br. 2 Claims App. (emphasis added).
Accordingly, we do not sustain the Examiner’s rejection of claims 1–
4, 6–18, 20, and 22 as unpatentable over Epstein, Lee, and Tichborne.

CONCLUSION
In summary:
Claims
Rejected
35 U.S.C.
§ 
Reference(s)/Basis Affirmed Reversed
1–4, 6–18,
20, and 22
103   Epstein, Lee, and
Tichborne
1–4, 6–18,
20, and 22

REVERSED