Shortages of parts are slowing F-35’s latest upgrade, which is on track to cost almost $1 billion more than expected. Hardware for the Technology Refresh-3 upgrade is not being produced fast enough by Lockheed Martin and other companies. The shortage isn’t the only reason for the delays, as there are also problems with software labs. This caused cost overruns, and Lockheed will face penalties as their contracts require them to deliver 52 upgraded jets this year. Lawmakers also questioned the decision to pause negotiations with Lockheed over a new five-year deal to sustain the F-35 fleet.