The U.S. Air Force is searching for answers on how to remedy supply chain bottlenecks in building engines for the service's F-15EX fighter by Boeing [BA] and F-16 by Lockheed Martin [LMT]. The Air Force "is embarking on a multi-year procurement of engines for its fighter fleet, with a projected peak demand of over 180 engines per year by FY 2034," according to a Monday business notice. "The current industrial base has demonstrated significant challenges, including production delays, quality control…