Lockheed Martin Corp. knowingly used substandard equipment to build F-22 Raptor stealth jets, according to a whistleblower lawsuit filed by a former engineer for the defense contractor. In the lawsuit, Darrol Olsen claims he was fired after complaining to supervisors that the company used defective stealth coatings on jets built between September 1995 and June 1999. The lawsuit asks Lockheed to pay $50 million for each of 183 F-22s built during that period.