European aircraft maker Airbus SAS has sued a partner of Boeing Co., Aviation Partners, Inc. (API) [Airbus SAS v. Aviation Partners Inc., 11cv1030, U.S. District Court for the Western District of Texas (Austin)], seeking to avoid paying patent royalties for wingtips that make its airplanes more fuel efficient.

“API’s threats [about royalties] are a significant hindrance to Airbus and, without an early resolution, place Airbus at a competitive disadvantage,” Airbus said in the complaint.

Airbus filed suit December 1, 2011 in US District Court in Austin, Texas, seeking a declaration that a patent owned by API is invalid and that Airbus’s own “sharklets” wingtips don’t infringe it.

The US patent at issue is number 5,348,253, filed in 1993 and issued in 1994, for a “blended winglet” first used in 1992:

The blended winglet is a wing-like device comprising a blended lifting surface attachable to each airplane wing tip so as to achieve minimum induced drag for a given surface size.

According to API, the winglets also reduce engine maintenance costs, airport noise, and emissions.

Since 1999, Aviation Partners has engaged in a joint venture with Boeing to manufacture the winglets, which are used on many aircraft including 2,800 Boeing jets.  Boeing was not named in the suit.

Airbus is adding sharklets to its planes to reduce fuel consumption by 3.5%.  Airbus and Boeing are engaged in vigorous competition over which can produce commercial aircraft with the lowest fuel consumption.  Airbus claims that its A320neo plane (equipped with sharklets) is more fuel efficient than the competing Boeing 737 Max.

The lawsuit claims that “For decades, Airbus has been developing and marketing wing tip devices that reduce drag and improve aircraft performance for various Airbus aircraft.”