By Lewis Krauskopf
(Reuters) - United Technologies Corp's Pratt & Whitney unit briefly suspended delivery of the engine for the F-35 Joint Strike Fighter jet in May because of questions about titanium provided to a parts supplier.
Pratt said on Friday it discovered conflicting documentation in late May that raised questions about the origin of the titanium, which was also used in parts for engines made by its Pratt & Whitney Canada division. The Lockheed Martin Corp F-35 strike fighter is the Pentagon's costliest weapons program.
Pratt determined very quickly that the material did not pose a flight safety risk, company spokesman Matthew Bates said in an emailed statement.
"While the tested material may not meet every Pratt & Whitney material control standard, our engine designs have significant amounts of margin and, based on our engineering assessments, such material does not pose a risk to safety of flight," Bates said.
Joe DellaVedova, a spokesman for the F-35 program office, agreed that the material does not pose a risk to flight safety and said the part "will be replaced by attrition."
Bates said Pratt reported its concerns at the time to the U.S. Pentagon's Defense Criminal Investigation Services unit, the Air Force Office of Special Investigations and the U.S. Attorney’s Office. A federal investigation is being conducted into the source of the titanium, whose origin remains unknown, DellaVedova said.
Pratt said it was no longer accepting parts made from material provided by the supplier, A&P Alloys. A&P Alloys did not immediately respond to requests for comment late on Friday.
Bloomberg News initially reported the titanium issue.
Engine deliveries for the F-35 program have been suspended since a separate June 23 incident, in which the engine on an Air Force training jet broke apart and caught fire just before takeoff from Eglin Air Force Base in Florida.
Company and military officials are investigating the cause of the Eglin incident. Bates said that Pratt and has a potential fix and plans to conduct tests next month.
United Tech shares closed down 1 percent at $107.98 on Friday.
(Reporting by Lewis Krauskopf; Editing by Jonathan Oatis, Bernard Orr)