now they killed F136 -a new problem with the P&W F135

www.flightglobal.com...

Pratt & Whitney is investigating how a "handful" of fan blade tips damaged an F135 engine during a ground test simulating the Lockheed Martin F-35's engine performance at supersonic speeds.

The programme's latest technical issue comes amidst a heated debate between the White House and Congress about continuing to fund the F135's rival engine - the General Electric/Rolls-Royce F136.

i honestly think there are binning the wrong engine here - the F135 should be killed off as its showing more and more fan blade failues from 1 reason or another

i dread the day 1 prototype bloes up because of engines failure.

Upon inspection, the errant parts were traced to several missing fan blade tips that somehow broke off. The parts were ingested into the compressor, which also sustained damaged in the first and second stages, P&W's expert says. The combustor and turbine stages escaped harm from the flying debris.

fan blade tips don`t just `break off` unless they hit somthing - the fan itsself wobbled and hit the casing im sure (IMO)

Pratt also says there should be no impact on F-35 flight testing, as the engine that failed has the "second-generation" IBR fan, which is lighter. The flight-test engines have the first-generation fan, which has already undergone durability testing, the company says. There is no halt to flight testing or engine ground testing, Pratt says.

Two other second-generation engines are on ground test and are being examined. The damaged engine should be repairable to retstart and complete qualification testing, the expert says. The fan will have to be replaced, but damage to the compressor blades is blendable and the rest of the turbomachinery looks undamaged.

ares blog.

F136 is not without its own problems either...

this fan was built to replace the first generation fan (which cracked and failed)

AWST

also whilst on the stand - and grounded the flight programme for a year


coupled with `stack ups` of fan bladesnot meeting specification


www.flightglobal.com...



as for the F136;

www.dodbuzz.com...

is that what you meant? a faulty bearing and sucking test equipment not bolted down properly into the engine?

The "new build" F136 engine first ran this January, had bearing problems, then was delayed till May. I might concede the F136 has had a smoother development so far, but it is behind. I don't think it is worth it to cancel the F135 because we hope the F136 will be smoother. And that would delay the F-35 even more.

this fan was built to replace the first generation fan (which cracked and failed)

My understanding is all previous difficulties had to do with the low pressure turbine, rather than the fan.

[edit on 15/9/2009 by C0bzz]

Pratt: F135 Fan Fix Simple, Cheap.

Pratt & Whitney says it's standard industry practice - clip the tip of a blade to remove the piece that's susceptible to damage. And that's what the manufacturer plans to do with the fan blades on its F135 engine for the F-35, after a piece of the tip of a first-stage fan blade broke off during durability testing.

Pratt says the "minor modification" to be made immediately to all ISR engines will be to clip the corner off the tip of the fan blade at its trailing edge, removing the piece that broke off and "alleviating the potential" for it to fail. This will not degrade the engine's performance, the company stresses.

Engines for flight-test F135s are not affected, although the bushings are the same, because they have a "first-generation" fan that has already passed the required durability testing. The ISR engine has a "second generation" fan with lighter integrally bladed rotors. The bushings will be inspected periodically for wear until a new design is developed under the F135 component improvement program.

That's not as bad as it might sound, because the blade damage occurred 2,455 cycles into a 2,600-cycle durability test of the initial service release (ISR) engine for production F-35As. That's the equivalent of eight years of in-service operation, Pratt says. When the tip broke off, the engine was 5 hours into a supersonic high-cycle fatigue test designed to deliberately excite blade vibration.

Graham Warwick

You probably want to read the comments on the page too. PW says it will not impact performance, but the comments on that page seem to indicate otherwise.

[edit on 19/9/2009 by C0bzz]

I agree with PW, and as I said just above, 'cropping' or 'tip-radius blends' are accomplished on a regular basis on ANY gas turbine engine when the tips or corners are damaged. (GE, RR, PW, CFM, etc...) Anyone not familiar with jet engine field repairs may think otherwise, but there isn't a performance issue here.

In the F100 series engine over 30 inches of blade leading and trailing edges may be removed by 'blending' before the fan is considered 'beyond limits'

NO production F135 will EVER operate in supersonic flight for 5 hours while experiencing 'maximum airflow'. Remember these are worse-case scenarios specifically designed to find weaknesses in the engine prior to them entering full scale production. There was no blade liberation, no catastrophic failure, no production delay, and no re-design of the fan as a whole.

*included example of cropping*

That_Engine_Guy
www.f-16.net...

[edit on 20/9/2009 by C0bzz]

theres many coments from both sides of the arguement all from `experts` that state that at this level of design , hacking off the top of the blade will or wont change the airflow and will or will not effect performance