The Patent Trial and Appeal Board (PTAB) designated as informative the decision in Ex parte Spangler, Appeal No. 2018-003800 (PTAB Feb. 20, 2019) (Bahr, APJ) (designated informative on Oct. 15, 2019), where the PTAB affirmed the examiner’s obviousness rejection based on design choice. The PTAB agreed with the examiner that the difference between the prior art and the claims would have been a simple design choice to one of skill in the art. Because the applicants failed to identify a stated problem/solution relating to the differentiating feature or any particular purpose for the differentiating feature, the PTAB agreed that the feature would have been an obvious design choice.

The applicants’ claims were directed to a featherseal for engagement with a turbine engine. The claimed featherseal included a particular arrangement of tabs that engage and seat in corresponding slots to axially position and retain the featherseal. Using a combination of two prior art references, the examiner found that it would have been obvious to add tabs from one prior art reference to the featherseal of another prior art reference in order to axially position the featherseal. The applicants did not appeal this portion of the examiner’s rejection.

The combination of prior art did not disclose the particular arrangement and relative size of tabs as recited in the claims, however. The examiner found that the claimed relative size and positioning of the tabs would have been a simple design choice because any arrangement or size would yield the expected result of axially positioning the featherseal. The applicants argued that the particular arrangement of the tabs was a “critical” feature, and pointed to various disclosures in the specification describing the benefits of the tabs. The PTAB agreed with the examiner that the tabs in any configuration would provide these benefits, and the relative sizes and particular locations of the tabs were immaterial to achieving the described benefits. The specification’s failure to disclose that the relative lengths and locations of the tabs solved any stated problem or were for any particular purpose confirmed that it would have been an obvious matter of design choice to resize and reposition the tabs, and would yield the predictable result of preventing axial movement.

The applicants also pointed to the prior art’s teaching of symmetric tabs—an arrangement contrary to the claimed asymmetric arrangement. The PTAB rejected this argument because although the prior art identified a symmetric arrangement as the preferred one, the reference taught asymmetric arrangements, all of which would have had the same benefit of properly positioning and seating the device. Accordingly, the PTAB affirmed the examiner’s rejection based on an obvious design choice.