# United States **Court of Appeals**  **for the Federal Circuit**

______________________ RAYTHEON TECHNOLOGIES CORPORATION, Appellant

v.

GENERAL ELECTRIC COMPANY, Appellee

ANDREW HIRSHFELD, PERFORMING THE FUNCTIONS AND DUTIES OF THE UNDER SECRETARY OF COMMERCE FOR INTELLECTUAL PROPERTY AND DIRECTOR OF THE UNITED STATES PATENT AND TRADEMARK OFFICE, Intervenor

______________________

2020

- 1755

______________________ Appeal from the United States Patent and Trademark Office, Patent Tri al and Appeal Board in No. IPR2018

- 01442.

______________________
Decided: April 16, 2021

______________________
L AUREN A NN D EGNAN , Fish & Richardson P

. C

. , Washington, DC, argued for appellant. Also represented by C HRISTOPHER D RYER , W ALTER K ARL R ENNER ; K ENNETH W AYNE D ARBY , Austin, TX; T IMOTHY R AWSON , San Diego, Case: 20-1755 Document: 51 Page: 1 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 2

CA; M ICHAEL V ALAIK , Bartlit Beck Herman Palenchar & Scott LLP, Chicago, IL

.

B RIAN E. F ERGUSON , Weil, Gotshal & Manges LLP, Washington, DC, argued for appellee. Also represented by D ANIEL M USHER , C HRISTOPHER P EPE ; A NISH R. D ESAI , New York, NY.

R OBERT J. M C M ANUS , Office of the Solicitor, United States Patent and Trademark Office, Alexandria, VA, for intervenor. Also represented by T HOMAS W. K RAUSE , F RANCES L YNCH , F ARHEENA Y ASMEEN R ASHEED

.

______________________
Before L OURIE , C HEN , and H UGHES , Circuit Judges

. C HEN , Circuit Judge

. A typical 35 U.S.C. § 103 obviousness case often turns on whether an asserted prior art reference teaches a particular disputed claim limitation or whether a skilled artisan would have been motivated at the time of invention tocombine the teachings of different references. There usually is no dispute about whether an asserted prior art reference is “self

- enabling,” i.e., whether a skilled artisan can make and use the subject matter disclosed in the reference.This appeal, however, requires us to consider when a reference needs to have a self

- enabling disclosure for supporting an obvious ness case. We have explained that there is no absolute requirement for a relied

- upon reference to be self

enabling in the § 103 context, so long as the overall evidence of what was known at the time of invention establishes that a skilled artisan could ha ve made and used the claimed invention. We have also previously expounded the principle that if an obviousness case is based on a non

- self

enabled reference, and no other prior art reference or evidence would have enabled a skilled artisan to make the cla imed invention, then the invention cannot be said to have been obvious. Case: 20-1755 Document: 51 Page: 2 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 3

In the present case, Raytheon 1 appeals a final inter partes review decision of the Patent Trial and Appeal Board (Board) finding claims 3 and 16 of U.S. Patent No. 9,695,751 (’751 pat ent) unpatentable as obvious in view of the Knip reference. In particular, the Board found that Knip discloses the claimed power density limitation for ageared gas turbine engine. During the proceeding, Raytheon submitted unrebutted evidence establishin g thatKnip’s disclosure of highly aggressive performance parameters for a futuristic turbine engine was based on the useof nonexistent composite materials. In response, the petitioner, General Electric Company (GE), never put forth any evidence suggesti ng a skilled artisan could have made a turbine engine with the power density recited in the claims. Because the relied

- upon prior art fails to enable a skilled artisan to make and use the claimed invention, we

reverse

. B ACKGROUND

A
Raytheon owns the ’751 patent, which is directed to gas turbine engines. See ’751 patent at Abstract. Gas turbine engines are commonly used for powering airplanes. At a high level, a gas turbine engine generally consists of a fan section, a compressor section, a combustor section, and a turbine section. See id. at col. 4 ll. 8

– 10. The compressor section typically includes a low

- pressure and high

- pressure compressor. See id. at col. 4 ll. 33

– 59. Similarly, the turbine section often consists of low

- and high

- pressure turbines. See id

.

1 United Technologies Corporation (UTC) is the original assignee of the ’751 patent. After the Board issued its final written decision, UTC merged with Raytheon Company to form Raytheon Technologies Corporation (Raytheon), the current owner of the ’751 patent. Case: 20-1755 Document: 51 Page: 3 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 4

Gas turbine engines produce thrust by drawing air into the front of the engine, mixing it with fuel and burning the mixture , and ejecting ex haust gasses. See id. at col. 4 ll. 12

– 17. Turbofan engines, a particular type of gas turbine engine relevant here, utilize an air bypass duct to increase thrust by ejecting some of the air through a bypass nozzle. Turbofan engines can be “direct

- drive ” or “geared.” In a direct

- drive engine, the fan is directly connected to the low

pressure compressor and turbine such that all three turn at the same speed. Alternatively, “geared” engines include a gearbox, allowing the turbine and compressor to rotate at a different, i.e., higher, speed than the fan. See id. at col. 1 ll. 37

– 46. When a compressor or turbine can spin at a higher rotational speed, it can perform the same amount ofwork in fewer stages. Fewer stages, in turn, leads to reduced volume an d weight of the turbine and the engine, resulting in greater efficiency.
The ’751 patent generally claims a geared gas turbine engine with two turbines and a specific number of fanblades and turbine rotors and/or stages. The key distinguishing feature of the claims is the recitation of a “power density” range that the patent describes as being “much higher than in the prior art.” See id . at col. 10 ll. 54

– 55. The ’751 patent defines power density as the “sea

- level

takeoff thrust” (SLTO thrust) divided by the engine turbine volume. See id. at col. 10 ll. 22

– 25 and claims 1, 15.

Claims 1

– 3 are reproduced in part below:

1. A gas turbine engine comprising:
a fan including a plurality of fan blades . . . ;
a compressor section;

a combustor in fluid commu nication with the compressor section; Case: 20-1755 Document: 51 Page: 4 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 5

a turbine section in fluid communication with the combustor, the turbine section including a fan drive turbine and a second turbine . . . ; and
a speed change system configured to be driven by the fan drive turbine to rotate the fan about the axis; and
a power density at Sea Level Takeoff greater than or equal to 1.5 lbf/in 3 and less than or equal to 5.5 lbf/in 3 and defined as thrust in lbf measured by a volume of the turbine section in in 3 measured between an inlet of a first turbine vane in said second turbine to an exit of a last rotating airfoil stage in said fan drive turbine.

2. The gas turbine engine as recited in claim 1, wherein the fan drive turbine has from three to six stages.

3. The gas turbine engine as recited in claim 2, wherein said number of fan blades is less than 18 and the second turbine has two stages.

Id. at claims 1

– 3. Independent claim 15 is substantively identical to claim 1 but requires the speed change system to have “a gear reduction.” See id. at claim 15. And claim 16, whichdepends from claim 15, contains the same additional limitation as claim 3. See id. at claim 16.

B
GE petitioned for inter partes review of claims 1

– 4, 9

– 10, 15

– 16, and 23 of the ’751 patent. See J.A. 102

– 89. GE’s Case: 20-1755 Document: 51 Page: 5 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 6

p etition relied on either Knip 2 or Gliebe 3 as a primary reference for its asserted unpatentability grounds. See J.A. 124

– 25. GE challenged claims 1

– 4, 9

– 10, and 15

– 16 as obvious in light of Knip alone and/or Knip in view of a secondary reference. See i d. GE also challenged claims 1

– 2 and 15 as anticipated by or rendered obvious by Gliebe, alone,and claim 23 as rendered obvious by Gliebe and a secondary reference. See id.
Knip is a 1987 NASA technical memorandum that envisions superior performance cha racteristics for an imagined “advanced [turbofan] engine” “incorporating all composite materials.” See J.A. 902. Although the construction of a turbofan engine incorporating such composite materials was undisputedly unattainable at that time (and, accord ing to the record, continues to this day to be beyond reality), an imagined application of these “revolutionary”composite materials to a turbofan engine allowed the author of Knip to assume aggressive performance parameters for an “advanced engine,” inclu ding then

- unachievable pressure ratios and turbine temperatures. See J.A. 906. Knip predicts that the use of these composite materialswould permit the resulting advanced engine to achieve significant reductions in engine volume and weight leading to “im provement in engine performance and thrust

- to

weight

- ratios.” See J.A. 903, 908. Although Knip disclosesnumerous performance parameters associated with its futuristic engine, it does not explicitly disclose SLTO thrust, turbine volume, or power density.
In its petition, GE argued that both Knip and Gliebe disclose performance parameters of a kind that would

2 G. Knip, Analysis of an Advanced Technology Subsonic Turbofan Incorporating Revolutionary Materials (May 1987) . J.A. 901

– 25.

3 P. Gliebe, Ultra

- High Bypass Engine Aeroacoustic Study (Oct. 2003) . J.A. 792

– 900. Case: 20-1755 Document: 51 Page: 6 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 7

permit a skilled artisan to derive the power density of their respective engines from those disclosed parameters. See J.A. 140

– 45
, 180

– 83. Accor ding to GE, those power densities render obvious or anticipate the claimed power density range, proving the challenged claims unpatentable. In thealternative, GE argued that because power density is a “result

- effective variable,” see J.A. 145

– 53, “even i f Knip did not disclose a turbine section volume and/or SLTO thrust that resulted in a power density within the claimed range,it would have nevertheless been obvious to a [skilled artisan] to modify the thrust and/or turbine volume for Knip’s engine to op timize the power density.” J.A. 726; see also J.A. 709.

After the Board instituted the inter partes review of the challenged claims, Raytheon disclaimed claims 1

– 2, 4, 9

– 10, 15, and 23, to “streamline” the issues, see Oral Arg. at 1:28

– 50, 3:57

– 4:24. T he disclaimer mooted all grounds relying on Gliebe, leaving only dependent claims 3 and 16, which were challenged exclusively on Knip

- based grounds. See J.A. 124

– 25. Despite its disclaimer, Raytheon relied solely on limitations within claims 1 and 15

— i.e ., the claimed power density range

— to argue the patentability of dependent claims 3 and 16 over Knip. 4 See, e.g., J.A. 4804.
Raytheon made two main arguments to the Board in support of claims 3 and 1 6’s patentability. First, it argued that GE’s expert employed a flawed methodology in deriving the power density of Knip’s advanced engine from the parameters that Knip disclosed. See id. Second, Raytheon

4 Disclaimed claims are treated as if they never existed, see Sanofi

- Aventis U.S., LLC v. Dr. Reddy’s Laboratories, Inc. , 933 F.3d 1367, 1373 (Fed. Cir. 2019), and disclaimer does not legally constitute “an admission that the subject of the disclaimer appears in the prior art,” National Fruit Products Co., v. C.H. Musselman Co ., 8 F. Supp. 994, 995 (M.D. Pa. 1934). Case: 20-1755 Document: 51 Page: 7 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 8

argued that Knip’s disclosure failed to enable a skilled artisan to make the claimed invention. See J.A. 4847

– 68. According to Raytheon, the aggressive parameters disclosedin Knip, and therefore, its power density, relied on “revolutionary” materials unavailable as of the priority date of the ’751 patent. J.A. 4855

– 58. In response, GE did not disput e that Knip’s contemplated revolutionary materials were unavailable at the time the ’751 patent was filed. See J.A. 6442. Nor did GE argue that the aggressive parameters disclosed by Knip, parameters GE used to calculate power density, were achievable th rough some other means. See J.A. 6440

– 43. Rather, GE argued that the issue of whether Knip enabled its advanced engine was “irrelevant” to the “question whether a [skilled artisan] reviewing Knip could make the [’] 751 Patent’s engine (using any already a vailable materials) without undue experimentation.” See J.A. 6442 (emphasis in original).

C
In its Final Written Decision, the Board determined that GE had met its burden of proving that claims 3 and 16 are unpatentable as obvious. See General Elec. Co. v. United Techs. Corp

., IPR2018

– 01442
, 2020 WL 859443, at *1 (P.T.A.B. Feb. 20, 2020). The Board treated enablementas a threshold issue, recognizing that it “could be dispositive of any analysis based on Knip in this proceeding.” I d. at *6. The Board ultimately concluded that Knip was “enabling,” see id. at *10, because it provided enough information to allow a skilled artisan to “determine a powerdensity as defined in claim 1, and within the range proscribed in claim 1,” id. at *29.
Having found Kn ip “enabling,” the Board concludedthat Knip rendered claims 3 and 16 obvious to a skilled artisan. See id. at *29

– 30. Like its enablement analysis, the Board’s overall conclusion focused on the narrow question of whether Knip provided enough disclosure to enable a Case: 20-1755 Document: 51 Page: 8 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 9

skilled artisan to calculate what would be the power density of Knip’s advanced engine. See id. at *29 (“We credit [GE’s expert’s] analysis [], which showed persuasively that [ a skilled artisan] would have used the engine cycle and turbine vol ume measurement parameters expressly provided in Knip, along with certain reasonable assumptions and estimates as to missing parameters, and obtained SLTO thrusts resulting in values within the claimed range

as set forth in claim 1.”). The Board further s upported its obviousness conclusion in view of Knip by concluding that, even if Knip’s power density did not fall within the claimed power density range, power density is a result

- effective variable. See id. at *23

– 27. Raytheon appealed to this court. We have jurisdiction under 28 U.S.C. § 1295(a)(4)(A).

D ISCUSSION Raytheon’s appeal presents a single issue: whether theBoard erred in finding Knip “enabling” of the claimed invention. According to Raytheon, the Board improperly focused only on whether Kni p enables a skilled artisan tocalculate the power density of Knip’s contemplated, futuristic engine, rather than also considering whether Knip enables a skilled artisan to make the claimed invention. Raytheon argues that, when viewed under the proper leg alstandard, nothing in the record demonstrates that Knip enables a skilled artisan to make the claimed invention. We
agree.
A
“Whether a prior art reference is enabling is a question of law based upon underlying factual findings.” Minn. Mining & Mfg. Co. v. Chemque, Inc. , 303 F.3d 1294, 1301 (Fed. Cir. 2002). We review the Board’s legal conclusions de novo and its underlying fa ctual determinations for substantial evidence. See In re Gartside , 203 F.3d 1305, 1316 (Fed. Cir. 2000). Case: 20-1755 Document: 51 Page: 9 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 10

To render a claim obvious, the prior art, taken as a whole, must enable a skilled artisan to make and use the claimed invention. See In re Kumar , 41 8 F.3d 1361, 1368 (Fed. Cir. 2005). In general, a prior art reference asserted under § 103 does not necessarily have to enable its own disclosure, i.e., be “self

- enabling,” to be relevant to the obviousness inquiry. See Symbol Techs., Inc. v. Opticon, In c., 935 F.2d 1569, 1578 (Fed. Cir. 1991) (“While a reference must enable someone to practice the invention in order to anticipate under § 102(b), a non

- enabling reference mayqualify as prior art for the purpose of determining obviousness under § 103.”); B eckman Instruments Inc. v. LKB Produkter AB , 892 F.2d 1547, 1551 (Fed. Cir. 1989) (“Even if a reference discloses an inoperative device, it is prior art for all that it teaches.”). For example, a reference that does not provide an enabling disclosure for a particular claimlimitation may nonetheless furnish the motivation to combine, and be combined with, another reference in which that limitation is enabled. See Apple Inc. v. Int’l Trade Comm’n , 725 F.3d 1356, 1365

– 66 (Fed. Cir. 2013). Alternatively, su ch a reference may be used to supply claim elements enabled by other prior art or evidence of record

. See Comcast Cable Commc’ns Corp. v. Finisar Corp. , 571 F. Supp. 2d 1137, 1145 (N.D. Cal. 2008), aff’d sub nom. Comcast Cable Commc’ns, LLC v. Finisar Cor p. , 319 F. App’x 916 (Fed. Cir. 2009). 5
But even though a non

- enabling reference can play a role in an obviousness analysis, the evidence of record must still establish that a skilled artisan could have made the claimed invention. As the Sixth Circuit aptly explained:

5 Comc ast presents an example where a prior art reference that was not enabled at the time of the publicationbecame enabled at a later date through advances in technology. See id. Case: 20-1755 Document: 51 Page: 10 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 11

The enabling disclosure co ncept [for a prior art reference] is a commonsense factor in making a determination of obviousness, for if neither any item of prior art, nor the background knowledge of one with ordinary skill in the art, would enable one to arrive at an invention, that i nvention would not be obvious. But to argue, as does [the patentee], that the sufficiency of each prior art teaching must betested under the strict standard requiring an enabling disclosure is to shift the emphasis from obviousness in light of the prior art, taken as a whole,to the sufficiency of each prior art teaching separately considered.
Minn. Mining & Mfg. Co. v. Blume , 684 F.2d 1166, 1173 n.10 (6th Cir. 1982); see also Beckman , 892 F.2d at 1551 (citing Minn. Mining with approval).

In the absence o f such other supporting evidence to enable a skilled artisan to make the claimed invention, a standalone § 103 reference must enable the portions of its disclosure being relied upon. See Ashland Oil, Inc. v. Delta Resins & Refractories, Inc. , 776 F.2d 281 , 297 (Fed. Cir.1985) (“The test of whether a particular compound described in the prior art may have been relied upon to show that the claimed subject matter at issue would have beenobvious is whether the prior art provided an enabling disclosure with r espect to the disclosed prior art compound.”); In re Hoeksema

, 399 F.2d 269, 274 (CCPA 1968) (“[I]f the prior art of record fails to disclose or render obvious a method for making a claimed compound .

. . it may not be legally concluded that the compound i tself is in the possession of the public [or obvious]

. ”). In this context the reference must necessarily enable the relied

- upon portion of its own disclosure

— the same standard applied to anticipatory references. In re Antor Media Corp. , 689 F.3d 1282, 12 90 (Fed. Cir. 2012) (“[A] prior art reference need not enable its full disclosure; it only needs to enable the portions of its disclosure alleged to anticipate the claimed invention.”). Case: 20-1755 Document: 51 Page: 11 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 12

B
We agree with Raytheon that the Board legally erred in its prior art enablement analysis. Here, the only prior art or other evidence GE relied on to establish that one of skill in the art would have been able to make a turbofanengine with the claimed power density was the Knip reference. But rather than determining w hether Knip enabled a skilled artisan to make and use the claimed invention, see Kumar

, 418 F.3d at 1368, the Board focused only on“whether [a skilled artisan] is provided with sufficient parameters in Knip to determine, without undue experimentation, a p ower density .

. . .” See Gen

. Elec. , 2020 WL 859443, at *7. This error propagates throughout the Board’s enablement analysis, see id. at *7

– 10, which fails to address whether Knip enables the claimed invention.
The Board defended its overly cramped inq uiry by noting that the claims at issue do not require the advanced materials recited by Knip. See id. at *7. Thus, according to the Board, whether Knip’s advanced engine had been or could be implemented “is not the proper consideration.” See id. (rejec ting Raytheon’s argument that Knip’s advanced engine must be “physically achievable based on the reference’s disclosure itself”); id. at *9 (“[E]nablement doesnot require that Knip’s advanced engine was actually implemented.” (citing Beckman , 892 F.2d at 1551) ) . On appeal, GE echoes the Board’s statements and goes further,claiming that “it is irrelevant whether Knip actually enables a [skilled artisan] to build the specific engine contemplated by Knip.” See Appellee’s Br. at 45. That position may have carried the day if GE had presented other evidence to establish that a skilled artisan could have madethe claimed turbofan engine with the recited power density. But no such other evidence was presented.
Thus, Knip’s self

- enablement (or lack thereof) is not only relevant to the enablement analysis, in this case it is dispositive. GE does not contend that the ’751 patent’s Case: 20-1755 Document: 51 Page: 12 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 13

turbofan engine is enabled by other prior art or evidence of record. Instead, GE relies solely on Knip’s disclosure. See

, e.g. , Appellee’s Br. at 48, 51. At oral argument, counsel for GE asserted that the Board determined , based on GE’s expert’s analysis, that Knip’s engine could have been in fact“successfully constructed, and therefore is enabled with respect to the claimed in vention.” See Oral Arg. at 27:19

– 29:00 (citing J.A. 42

– 44, 781). We disagree that the Board made such a finding. Moreover, GE neglected to mention that what its expert “constructed” was a computer model simulation of Knip’s imagined engine, see J.A. 781 , not a physical working engine. GE’s expert never suggested that a skilled artisan could have actually built such an engine.
In contrast, Raytheon presented extensive, unrebutted evidence of non

- enablement. Raytheon submitted and relied on a declarati on from Dr. Williams, a professor of materials science, detailing the unavailability of the revolutionary composite material contemplated by Knip. See J.A. 4853

– 68, 6291

– 311. Additionally, Raytheon submitted evidence that the exceptional temperature and pressure parameters cited in Knip had not been achieved through other means as of the priority date. See J.A. 4856

– 58 (citing the supplemental declaration of Dr. Spakovsky (J.A. 4913

– 22)). Raytheon’s unrebutted evidence that Knip fails to enable a skille d artisan to physically make Knip’s advanced engine is conclusive, given that this was the only evidence GE presented for why a skilled artisan could achieve the claimed power density.
In sum, we conclude that GE failed to provide an evidence

- based cas e for how the turbofan engine claimed inthe ’751 patent having a particular power density is enabled by Knip’s disclosure. Thus, the Board’s finding that Knip is “enabling” is legal error.

C

GE’s back

- up argument that the Board’s decision can be affirme d on the basis of its result

- effective variable Case: 20-1755 Document: 51 Page: 13 Filed: 04/16/2021RAYTHEON TECHNOLOGIES CORP

. v. GENERAL ELECTRIC COMPANY 14

finding suffers from the same enablement

- based flaw. Even if the Board were correct that power density and other performance characteristics are variables a skilled artisan would want to optimize, GE’s argum ent is predicated on a skilled artisan “modify[ing] the thrust and/or turbine volume for Knip’s engine to optimize the power density.” See J.A. 726. If a skilled artisan cannot make Knip’s engine, a skilled artisan necessarily cannot optimize its power d ensity.

C ONCLUSION We have considered GE’s remaining arguments and find them unpersuasive. For the reasons set forth above, we reverse the Board’s decision finding claims 3 and 16 of the ’751 patent unpatentable as obvious.

REVERSED Case: 20-1755 Document: 51 Page: 14 Filed: 04/16/2021