PlayLoud
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U.S. Military Grounds F-35 Fighter Jets

Fri Feb 22, 2013 8:31 pm

http://news.blogs.cnn.com/2013/02/22...ounds-f-35-fighter-jets/?hpt=hp_t3

Quoting CNN:

The Pentagon's most expensive weapons system is going to spend some time on the bench.

The U.S. military on Friday grounded the F-35 fighter jet due to a crack in an engine component that was discovered during a routine inspection in California.

The Pentagon said in a statement that it was too early to assess the impact on the nearly $400 billion fleet of jets designed for use by the Navy, Air Force and Marines.

This story is developing. We'll have more shortly.
 
ThePointblank
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RE: U.S. Military Grounds F-35 Fighter Jets

Sat Feb 23, 2013 12:14 am

The issue is a defect in the low pressure turbine blades of one of the engines. Possible that it is due to a casting issue or a similar story to UA 232 where the original ingot had defects in it, but that's conjecture. Nothing to be too terribly concerned about unless it is a traceable quality control issue, so this is a grounding for safety's sake and to cover all of the bases. I expect that once inspections are complete, the jets will resume flying.

I will also note that F-35 is still a fighter in testing, and since this occurred at Edward AFB, there will be more 'routine' inspections, including engine borescope looks, just to see how the fighter ages with use.
 
checksixx
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RE: U.S. Military Grounds F-35 Fighter Jets

Sat Feb 23, 2013 5:22 am

Sounds a little bit like overkill to me...I asked this on another forum, but does anyone know if these blades are DS single crystal??
 
Oroka
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RE: U.S. Military Grounds F-35 Fighter Jets

Sat Feb 23, 2013 2:09 pm

Seems cracks and defects have never been found in a turbine blade before (ever) and this is a massive failing of the F-35.

Seems the routine inspections are doing what they are supposed to be doing. Imagine that.


Why not 'Vigilant F-35 maintainers catch defective turbine blade'? Cause 'U.S. Military Grounds F-35 Fighter Jets' gets more attention.
 
Powerslide
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RE: U.S. Military Grounds F-35 Fighter Jets

Sat Feb 23, 2013 5:20 pm

Quoting Oroka (Reply 3):
Why not 'Vigilant F-35 maintainers catch defective turbine blade'? Cause 'U.S. Military Grounds F-35 Fighter Jets' gets more attention.

There is no news like bad news. "Maintainers doing their job" doesn't sell very well at the stands. If you can't feed the people BS through fear and lies then what is the point of news articles?
 
sphealey
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RE: U.S. Military Grounds F-35 Fighter Jets

Sat Feb 23, 2013 6:48 pm

Do fighters have the same requirement for a 1st-stage blade-off test as transport category aircraft [1]?

sPh

[1] Whether civilian or military, since new military transport developments also certify to civilian regs
 
ThePointblank
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RE: U.S. Military Grounds F-35 Fighter Jets

Fri Mar 01, 2013 11:44 pm

We are back in the air:
http://www.reuters.com/article/2013/...heed-fighter-idUSBRE91R1IT20130301

Quote:
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 rescind the grounding order after extensive tests and analysis of the cracked turbine blade, which was discovered on February 19 during a routine inspection conducted after every 50 hours of flight time.

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.
 
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Aesma
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RE: U.S. Military Grounds F-35 Fighter Jets

Sat Mar 02, 2013 8:50 pm

The CNN "journalist" has obviously no idea of what he's talking about since he implies there is a big fleet of F-35 and that the grounding means a loss of defense capability when in fact the airplane is far from being in service.
New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
 
Oroka
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RE: U.S. Military Grounds F-35 Fighter Jets

Wed Mar 06, 2013 7:21 pm

But it doesnt matter that it wasnt a design defect. Being an engine that was subjected to 4x its designed operational levels has no bearing to the fact that the F-35 is horrible and wasnt perfect right off the drafting table (I know, computer aided design).


It is a good thing for the F-35 that it wasnt a design problem, or even a quality control problem, but good things for the F-35 are non topics.
 
ThePointblank
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RE: U.S. Military Grounds F-35 Fighter Jets

Fri Apr 12, 2013 9:03 pm

Another update: The failure was most likely caused by the casting process:
http://www.flightglobal.com/news/art...aced-to-casting-process-pw-384624/

Quote:
The analysis indicates that the Lockheed Martin F-35 engine blade cracked despite being made correctly according to the blueprint for making the part, Croswell says. That finding points to a flaw in the casting process itself.

"There may be features in the castings that are allowed by the blueprint, but now we've learned that those features we should not allow," Croswell says.

P&W can either change the process used to make the casting of the turbine blade or simply throw out any blade that shares similar features of the one that cracked.

"It may be as simple as culling those blades that have that feature," Croswell says.

P&W is finalising an analysis of which option would be most affordable, and that report will be submitted to the joint programme office at the end of June.

Add the unusual operating perimeters of the engine in question, and you have a crack.
 
B727LVR
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RE: U.S. Military Grounds F-35 Fighter Jets

Wed Apr 17, 2013 2:42 am

Quoting ThePointblank (Reply 1):
Nothing to be too terribly concerned about

I'm sure those flying a single engine aircraft engine would politely disagree with you on that.

At least the cracks were found before something serious happened!
I'm like a kid in a candy store when it comes to planes!

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