"At this time, I do not have sufficient information to return the
F-35B and F-35C fleet to flight," Vice Admiral David Dunaway, who
heads the Navy's Air Systems Command, said in an update to a
fleetwide grounding order issued by U.S. officials on July 3. A copy
of the document was obtained by Reuters.
Dunaway said in the document that he was committed to returning the
F-35 fleet to flight as soon as possible, but there was "no
discernible event that represents a root cause."
In the incident on June 23, the Pratt & Whitney engine on an Air
Force F-35 A-model jet broke apart and caught fire while a pilot was
preparing to take off from a Florida air base.
Until the grounding is lifted, the U.S. Marine Corps and Britain
will not be able to ferry four F-35B aircraft to Britain for the
jet's planned international debut at two air shows there this month
- the Royal International Air Tattoo, the world's largest military
air show that began Friday, and the Farnborough air show, which
starts on Monday and runs until July 20.
It would be a huge embarrassment to the United States if the jets
are unable to appear at either air show, and could jeopardize export
prospects for the new radar-evading plane just as two initial
partners on the program - Canada and Denmark - are weighing fresh
The engine failure had also prevented the F-35 from making an
appearance at the July 4 naming ceremony for Britain's new aircraft
Dunaway said the Navy and other services are continuing to
investigate the incident, and planned to update the flight directive
no later than July 16 - two days after the start of the high-profile
Farnborough air show outside London.
Lockheed spokesman Michael Rein said the company still hoped the
jets could be cleared to fly in time to make the show.
"We remain hopeful the grounding will be lifted in time for them to
appear at Farnborough," he said.
Dunaway's memorandum did not rule out the possibility that the most
advanced U.S. fighter jet could still appear at the tail end of the
Farnborough air show, but the prospects of that occurring appeared
to be dimming fast.
"There are specific additional evaluation conditions required to
support the Farnborough air show in the UK, including the ferry
flight across the Atlantic and performance in the air show itself.
Additional work is required in order to understand and mitigate air
show unique risks," it said.
[to top of second column]
Four Marine Corps F-35B jets are waiting at a Maryland air base to
fly across the Atlantic, and a UK jet that had been due to join them
remains at Eglin Air Force Base in Florida.
The U.S. jets were ready to fly as soon as the grounding order was
rescinded, said one person familiar with the situation.
Dunaway said the current analysis would have to be refocused to
potentially meet the timeline for the F-35's participation in the
Farnborough air show. The jets need a full day in Britain to allow
for any maintenance or repairs before they participate in flying
Dunaway said officials were looking at possible operational
restrictions for the jets while the issue was still being
investigated, and would also likely implement repeated engine
inspections to monitor for any indication of a future problem. But
those measures would take several more days to complete.
It remains unclear what caused the third stage of the Pratt engine
to break apart and burst through the top of the airplane. The
incident severed a fuel line, which then caused a fire.
Frank Kendall, the Pentagon's chief weapons buyer, told U.S.
lawmakers on Thursday there was "growing evidence" that the incident
was an individual event and had not been caused by a systemic issue.
He said all existing engines had been inspected and that no issues
similar to the one that caused the engine failure had been found,
but he said safety was the Defense Department's top priority.
(Editing by Sandra Maler, Ken Wills and Pravin Char)
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