United Technologies Corp. unit Pratt & Whitney has mounted a new challenge to a patent held by Rolls-Royce PLC for blades used in jet engines, accusing Rolls-Royce of misleading the U.S. Patent and Trademark Office in order to obtain the patent. Pratt & Whitney announced Monday that it had filed a complaint against Rolls-Royce in the U.S. District Court for the District of Connecticut over the patent. Back in May, Rolls-Royce accused Pratt & Whitney of infringing U.S. Patent Number 6,071,077, titled “Swept fan blade” at the U.S. District Court for the Eastern District of Virginia. Pratt & Whitney argues in the current suit that Rolls-Royce engaged in unfair behavior to mislead the USPTO into issuing the patent-at-issue that the Rolls-Royce patent is invalid, unenforceable. The challenge also states that Rolls-Royce is unlawfully using its patent and taking other actions in an attempt to harm Pratt & Whitney. Finnegan is representing Pratt & Whitney.