Pratt & Whitney Halted F-35 Engine Delivery Over Titanium

United Technologies Corp.’s Pratt & Whitney unit said it suspended delivery of engines for the F-35 jet, the Pentagon’s costliest weapons program, over concern that a supplier may have provided “suspect” titanium.

Delivery of engines was halted in May after an in-house inspection and testing process “raised questions about the origin” of the titanium, spokesman Matthew Bates said in an e-mailed statement. The company replaced all the suspect engine parts in its inventory for failing to meet specifications, but determined that the metal in 147 F-35 engines already delivered didn’t pose a flight-safety risk, he said.