By Andrea Shalal-Esa
WASHINGTON Feb 27 The Pentagon said on
Wednesday that no additional cracks have been found on F-35
fighter engines during inspections begun after the Feb. 19
incident that halted flights of the entire fighter fleet, and
operation of the engines on the ground.
Kyra Hawn, spokeswoman for the F-35 program office, said
officials were continuing to investigate a cracked engine blade
found on a test plane at Eglin Air Force Base in Florida, with
engineers at enginemaker Pratt & Whitney due to break open the
affected engine blade for further study on Wednesday.
Pratt, a unit of United Technologies Corp, supplies
the engine for the single-engine, single-seat fighter plane,
which is built by Lockheed Martin Corp.
The Pentagon announced the grounding of all F-35 warplanes
on Friday after an inspection revealed a crack on a turbine
blade in the jet engine of an F-35 being tested at Edwards Air
Force Base in California.
It was the second engine-related grounding in two months of
the $396 billion F-35 Joint Strike Fighter, the Pentagon's
largest weapons program. The Marines Corps version of the plane
was grounded for nearly a month starting in mid-January because
of a faulty hose in the engine.
Hawn said inspections were under way of the engines on all
51 F-35 jets in the Pentagon's inventory, as well as additional
engines that are spares or on planes being assembled by Lockheed
at its Fort Worth, Texas, plant.
None of the engines inspected thus far had shown similar
cracks to the one found on the Florida test plane, she said.
She said nondestructive testing of the cracked turbine blade
had been completed, including microscopic tests and X-rays, with
additional "destructive" testing scheduled for Wednesday,
including a test in which the blade will be "fractured" open for
closer examination of the surface.
She said the Pentagon would announce further details when
the engineering investigation was complete.
Sources familiar with the investigation told Reuters on
Tuesday that Pratt & Whitney is 99 percent sure the problem with
the turbine problem that grounded the Pentagon's F-35 fleet was
not caused by high-cycle fatigue, which could force a costly
Pratt officials have also largely ruled out a manufacturing
defect, according to two sources briefed on the investigation,
who said the company was recommending the resumption of ground
operations of the engine as early as Wednesday, and a return to
flight operations later this week.
Tests completed on Tuesday supported that view, pointing to
a "creep structure rupture" caused by the fact that the engine
on that particular test plane had been run particularly hard at
hot temperatures since it was used for after-burner testing,
said the two sources, who were not authorized to speak publicly.
Current engines would not reach the same "hot time" for
years, Pratt engineers have said, which would allow the Pentagon
to impose incremental limits on engine use and monitor them for
possible component replacement, one of the sources said.
"Basically this engine was run for an extraordinary amount
of time at very high power in a short period of time," said the
source, who was not authorized to speak publicly.
Pratt had no comment on the state of the investigation.
The top uniformed officers in the Air Force, Navy and Marine
Corps are due to meet on Thursday for a long-scheduled meeting
about the F-35, but they are slated to discuss bigger issues
such as when the services can start using the new warplanes for
military operations, according to a defense official familiar
with the meeting. The services must provide estimated dates for
"initial operating capability" to Congress by June 1.
The service chiefs would also discuss a new Pentagon drive
to use competition to reduce the staggering cost of operating
and maintaining the new jets, a sum now forecast at over $1
trillion over the next decades, the source said.
Lieutenant General Christopher Bogdan, who runs the F-35
program for the Pentagon, slammed Pratt and Lockheed during an
air show in Australia earlier on Wednesday, accusing the
companies of trying to "squeeze every nickel" out of the U.S.
government and failing to see the long-term benefits of the
Hawn said a separate incident involving temperature control
equipment built by Honeywell International Inc has been
deemed a "minor test discovery, with no impact to safety of
flight or operations."