F-35 to return to flight after grounding

F-35 to return to flight after grounding
By AUSTIN WRIGHT | 28 Feb 2013

Lockheed Martin's F-35 Lightning II is returning to flight after its grounding last week over a crack discovered in an engine blade aboard an Air Force-model jet, POLITICO has learned.

The decision is effective immediately, said Joe DellaVedova, a spokesman for the Defense Department’s F-35 Joint Program Office. Pentagon officials were planning to issue a statement on the decision later Thursday evening.

[...]

Source: http://www.politico.com/story/2013/02/f ... 88277.html

Pentagon says to resume F-35 flights 28 Feb 2013 by Andrea Shalal-Esa

"(Reuters) - The Pentagon said on Thursday it would resume flights of its F-35 fighter jets, which were grounded a week ago after a crack was discovered in an engine of a test plane.

"F-35 flight operations have been cleared to resume," Pentagon spokeswoman Kyra Hawn said.

No additional cracks were found during inspections of engines in the rest of the F-35 fleet or in any spare engines, Hawn said.

Matthew Bates, a spokesman for Pratt & Whitney, which supplies the engines for the planes, said the Pentagon's F-35 program office had decided to lift a temporary suspension of flight operations after it conducted extensive tests on the affected engine part. The tests showed that a crack in a turbine blade stemmed from the "unique operating environment" in flight tests rather than a design flaw, he said.

Bates said Pratt had been working around the clock with Pentagon officials to determine the cause of the crack in the engine blade.

"The team has determined that root cause is sufficiently understood for the F-35 to safely resume flight," Bates said.

The engine in question had operated at high temperatures more than four times longer than a typical F-35 flight, which led to a separation of the "grain boundary" of this particular blade, he said.

[...]

Source: http://www.reuters.com/article/2013/03/ ... mesticNews

Lockheed F-35 Flights Permitted to Resume, Pentagon Says
By Tony Capaccio - Feb 28, 2013 8:47 PM

Flights of Lockheed Martin Corp. (LMT)’s F-35 will be allowed to resume, the U.S. Defense Department said, ending a suspension that grounded the fleet after the discovery of a cracked engine blade in one of the stealth jets.

The affected engine had been subjected to “prolonged exposure to high levels of heat and other operational stresses” in testing, the Pentagon F-35 office said today in a statement.

Enlarge image Lockheed F-35 Flights Permitted to Resume, Pentagon Says
Lockheed F-35 Flights Permitted to Resume, Pentagon Says Lockheed F-35 Flights Permitted to Resume, Pentagon Says Lockheed Martin Corp. via Bloomberg
An undated handout photograph shows Lockheed Martin Corp.'s F-35 fighter jet, provided to the media on Thursday, Dec. 8, 2011.

An undated handout photograph shows Lockheed Martin Corp.'s F-35 fighter jet, provided to the media on Thursday, Dec. 8, 2011. Source: Lockheed Martin Corp. via Bloomberg
Inspections of other F-35 fighter jets didn’t find any other “cracks or signs of similar engine stress,” and no redesign will be needed for the engines built by United Technologies Corp. (UTX)’s Pratt & Whitney unit, according to the statement.

The F-35, the Pentagon’s most expensive weapons program, has been plagued by a costly redesign, bulkhead cracks, excessive weight and delays in software that have helped put it seven years behind schedule. The cost of the program’s 2,443 aircraft is now estimated at $395.7 billion, a 70 percent increase since 2001.

The flight suspension was ordered Feb. 22 after a routine engine inspection revealed a crack in a turbine blade on a test aircraft at Edwards Air Force Base in California. The grounding was undertaken as a “precautionary measure,” the Pentagon’s F- 35 office said that day in a statement.

The decision to end the suspension came after Pratt & Whitney recommended that flight operations be restored.

Eighth Batch
Lockheed Martin, the world’s largest defense contractor, earlier today received a $333.7 million down payment to buy initial parts, components and materials for an eighth batch of F-35s, as the Pentagon locked in the funds hours before automatic U.S. budget cuts were set to take effect.

The action exempts the funds from the across-the-board spending reductions known as sequestration that begin tomorrow, because Pentagon officials have said contracts with obligated dollars won’t be cut or terminated. The eighth contract calls for 35 jets, including four aircraft for the U.K. and two for Norway, according to a Pentagon statement.

Source: http://www.bloomberg.com/news/2013-03-0 ... -says.html

F-35s cleared to resume flight operations
28 Feb 2013 Dave Majumdar

"The suspension of F-35A flight operations has been lifted for the air force," the USAF says.

USAF F-35 flight operations at Eglin AFB, Florida, will resume on 5 March because 4 March is a previously scheduled maintenance training day, service officials say. The US Marine Corps' short take-off vertical landing F-35Bs will resume flying at the Florida base on 1 March. "The Marines' F-35B will fly tomorrow afternoon at Eglin," the USAF says.

Operations at other bases are also cleared to be resumed....

...The JPO adds that the engine does not need to be redesigned is required as a result of this event."

Source: http://www.flightglobal.com/news/articl ... ns-382909/

kamenriderblade wrote:Is it me, or does the rear horizontal tail need to have a wider gap between it and the flame?

Pentagon says to resume F-35 flights
By Andrea Shalal-Esa / Reuters

Bates [Pratt spokesman] said Pratt engineers had been working around the clock with Pentagon experts to determine the cause of the crack in the engine blade, including a "destructive" test that cracked open the blade.

The tests showed that the crack resulted from the "unique operating environment" in flight tests -- many of which tested the engine's powerful after burners -- rather than a high-cycle fatigue crack, which would have required a design change.

Bates said the engine in question had operated at high temperatures for more than four times longer than a typical F-35 flight, which led to a separation of the "grain boundary" of this particular blade.

The Navy order rescinding the flight ban, or so-called "red stripe," said that engine had experienced the most "hot engine time exposure" of all the engines in the developmental program. It said it would now require reports to monitor and limit similar damage after every 25 flight hours.

Pratt recommended the resumption of flights and ground operations of the engine earlier on Thursday after its engineers ruled out a high-cycle fatigue crack.

The Pentagon said the investigation concluded that the 0.6-inch long crack was caused by "prolonged exposure to high levels of heat and other operational stressors.

Source: http://www.reuters.com/article/2013/03/ ... nnel=11563

Op-Ed: The F-35’s Afterburning Engine Can’t Stand Heat
Defense-aerospace.com; published March 1, 2013
By Giovanni de Briganti

[...]

I recall the A4G (and E/F with the 9,300lb thrust J52-P8 engyn) had a full power (no A/B) restriction of 5 minutes at any one time with perhaps further restrictions according to other criteria (I would have to reference NATOPS) per flight with monitoring of EGT (Exhaust Gas Temperature) so as not to exceed limits. Exceed limits and bad fings would happen. Anyway go read the article.

[...]

Source: http://www.defense-aerospace.com/articl ... -heat.html

Pentagon resumes flights of F-35 jets after grounding the entire $400B fleet for a week
By Reuters Reporter 01 Mar 2013

[...]

...Bates said Pratt engineers had been working around the clock with Pentagon experts to determine the cause of the crack in the engine blade, including a 'destructive' test that cracked open the blade.

The tests showed that the crack resulted from the 'unique operating environment' in flight tests -- many of which tested the engine's powerful after burners -- rather than a high-cycle fatigue crack, which would have required a design change.

Bates said the engine in question had operated at high temperatures for more than four times longer than a typical F-35 flight, which led to a separation of the 'grain boundary' of this particular blade.

The Navy order rescinding the flight ban, or so-called 'red stripe,' said that engine had experienced the most 'hot engine time exposure' of all the engines in the developmental program. It said it would now require reports to monitor and limit similar damage after every 25 flight hours....

[...]

Source: http://www.dailymail.co.uk/news/article ... paign=1490

F-35 Engine Issue Isolated: Fleet Cleared for Flight
Amy Butler / AvWeek

[...]

The crack was found in AF-2, which has been used for testing the aircraft at the edge of its operational envelope. "The engine in question is part of the F-35 test aircraft fleet and had been operated for extended time in the high-temperature environment in its mission to expand the F-35 flight envelope," according to a statement from Lt. Cdr. Kyra Hawn, an F-35 spokeswoman. "Prolonged exposure to high levels of heat and other operational stressors on this specific engine were determined to be the cause of the crack."

[...]

However, this incident raises questions about the durability of the engine which pushed to its limits. AF-2 was used to test the new horizontal tail skin, and so it was run through many extra afterburner tests. Officials are sure to implement additional inspections and monitoring actions to understand more about the durability of these engines in extreme conditions.

[...]

Source: http://www.aviationweek.com/Blogs.aspx? ... ction=true

Lockheed Martin F-35 F135 Engine Fast Facts (Interactive Display Loop) HD
Uploaded on Nov 23, 2011

http://www.youtube.com/watch?feature=pl ... _dFIA58uuE

"Pratt & Whitney's F135 propulsion system is the engine for the new advanced, single-engine tactical fighter, the F-35 Lightning II, developed by Lockheed Martin. The F-35 has unique capabilities for conventional takeoff and landing (CTOL), carrier-variant (CV), and short takeoff and vertical landing (STOVL). The same F135 engine will power all three variants."

the32notes wrote:correct me if i'm wrong gents,

but was the delamination of the tail the cause of the downgraded acceleration and sustained G loads.

Finally!!! I was looking in the 2011 report, explains why I didn't find it...

Anyway page 30 in
http://www.dote.osd.mil/pub/reports/FY2012/

Horizontal tail surfaces are experiencing higher
than expected temperatures during sustained
high-speed / high-altitude flight, resulting in
delamination and scorching of the surface coatings
and structure. All variants were restricted from
operations outside of a reduced envelope until the
test team added instrumentation to the tailbooms to
monitor temperatures on the tail surfaces.

best regards