cubastar
Topic Author
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Joined: Wed Nov 15, 2006 11:48 pm

Design Flaw In PW4000 - FAA Directive

Thu Mar 22, 2012 7:52 pm

FAA will propose Directive tomorrow, March 23. It involves replacing the first stage turbine hub prematurely in 964 engines being used under US registry.

http://www.flightglobal.com/news/art...f-pw4000-turbine-directive-369855/
 
tdscanuck
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RE: Design Flaw In PW4000 - FAA Directive

Thu Mar 22, 2012 8:58 pm

Quoting cubastar (Thread starter):
It involves replacing the first stage turbine hub prematurely in 964 engines being used under US registry.

From the life limits in the flightglobal article, it looks like they pulled the life back by ~10%. That means this shouldn't trigger a spate of immediate replacements, just some replanning of the engine change schedules.

How often does a PW4000 come off for life limit, as opposed to EGT degradation? If it's mostly the latter then this AD might not actually influence the fleet much.

Tom.
 
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lightsaber
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RE: Design Flaw In PW4000 - FAA Directive

Sun Mar 25, 2012 12:32 am

Quoting tdscanuck (Reply 1):
How often does a PW4000 come off for life limit, as opposed to EGT degradation?

Ten years ago the #1 reason was deteriorating fuel burn. (All engines deteriorate fuel burn with wear. And yes, EGT and fuel burn are tied... Engines were being pulled before EGT limits as fuel burn was impacting payload.)


Now there have been improvements in the PW4000... I do not know what is driving the fleet today.

Lightsaber
"They did not know it was impossible, so they did it!" - Mark Twain

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