By Doug Cameron 

The Pentagon on Thursday said its fleet of Lockheed Martin Corp. F-35 combat jets was grounded to investigate engine problems that may have caused a Marine Corps plane crash last month.

Officials said most of the global fleet of about 320 jets could be grounded for up to 48 hours while investigators inspect fuel tubes in engines that are made by Pratt & Whitney, a unit of United Technologies Corp.

"If suspect fuel tubes are installed, the part will be removed and replaced," said the F-35 Joint Program Office, which oversees the purchase and operation of the planes. Lockheed Martin said in a statement that it is supporting the review and working with Pratt & Whitney to "limit disruption to the fleet."

Pratt & Whitney didn't immediately respond to a request for comment. United Technologies shares were up 1% on Thursday while Lockheed Martin shares fell about 2%.

The grounding comes amid a debate over the reliability and safety of U.S. military aircraft. Defense Secretary Jim Mattis recently called for improvements to the fleet. Military officials have said the airfleet suffered from budget cuts in recent years that the Trump administration has reversed.

The F-35 fleet was temporarily grounded in 2014 following a fuel tank fire on a jet preparing for takeoff. Pratt & Whitney paid for repairs and a design fix to resolve the issue.

The F-35B jet that crashed in South Carolina on Sept. 28 is a different model. The pilot ejected safely.

The F-35B has a single Pratt & Whitney engine and a lift fan made by Rolls-Royce Holdings PLC that allows it to take off and land vertically.

Britain's Ministry of Defense, which is conducting trials of the jet on an aircraft carrier off the U.S. East Coast, said Thursday that it was inspecting its planes as well. One plane resumed flying Wednesday after inspectors found the part under scrutiny wasn't in use on the jet.

The F-35, used by the U.S. Air Force and the Marine Corps, is also due to start flying from Navy aircraft carriers next year. Italy, the Netherlands, Israel and Norway are also flying the planes.

Lockheed Martin earlier this month secured a $11.5 billion deal for the next batch of F-35 jets, which included new incentives and penalties to improve its production performance after some planes were delivered late. The company had to freeze production for a time earlier this year because of a separate fuel-system problem.

--Robert Wall contributed to this article.

Write to Doug Cameron at doug.cameron@wsj.com

 

(END) Dow Jones Newswires

October 11, 2018 12:48 ET (16:48 GMT)

Copyright (c) 2018 Dow Jones & Company, Inc.
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