A filing Wednesday in U.S. District Court gave notice the former employees are taking the case to the 10th Circuit Court of Appeals. At issue is a federal judge’s decision that they failed to show Boeing defrauded the U.S. government in a $1.6 billion contract.

U.S. District Judge Monti Belot summarily ruled Oct. 8 in favor of Boeing and California-based supplier Ducommun Inc., rejecting claims brought by former workers Taylor Smith, Jeannine Prewitt and James Ailes.

Their 2005 lawsuit alleged that Boeing defrauded the government in a contract for two dozen 737 Next Generation aircraft by using “bogus parts.”