B737200
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Distorted Turbine Blades

Mon Nov 09, 2009 9:46 am

Hi,

I have a quick question, at my local airport there is an abandoned 720, I was looking at its engines and the fan has these notches in dented into them.

Anyone know what could have caused hem and can the plane safely fly with them? - I am attaching a picture below. - I don't think they were caused during a singular event but over time, maybe due to particle ingestion, etc.

I am hoping to use this "phenomena", for lack of a better word, in a degradation assignment I have to do. Any nudges in the right direction would be greatly appreciated.

Thanks in advance.

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oly720man
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RE: Distorted Turbine Blades

Mon Nov 09, 2009 10:54 am

I presume the aircraft is N720JR, covered in an old thread here
Still Any Chance To Fly On B720? (by Birdwatching Jan 24 2006 in Civil Aviation)

The link to naharnet doesn't work, but I think this is what it should have linked to

http://www.naharnet.com/domino/tn/Ne...003eddc1?OpenDocument&PRINT&Click=

The damage as shown could have been a bird strike, or some other FOD. It does look like the damage moves outboard from blade to blade with the rotation being anticlockwise.

Look at the whole engine, if you can, and see if any of the fixed blades have any leading edge damage as well. Damage over a longer period would have been over the whole engine and more uniform. Such localized damage could only really have come from a one-off event.

The plane was grounded with 31 defects. Maybe the damaged blades was one of them.
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747classic
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RE: Distorted Turbine Blades

Mon Nov 09, 2009 12:30 pm

Quoting B737200 (Thread starter):
I have a quick question, at my local airport there is an abandoned 720, I was looking at its engines and the fan has these notches in dented into them.

Anyone know what could have caused hem and can the plane safely fly with them?

The blades concerned are fanblades or first stage compressorblades. The first row of blades are the fixed inlet guide vanes.
The round edges (no sharp cut-outs) suggest that these fan blades are "reworked" blades.
It is possible with metal fan blades to rework them, when the (FOD) damage is within limits of the engine manufacturer.

[Edited 2009-11-09 04:33:06]

[Edited 2009-11-09 04:35:32]
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EMBQA
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RE: Distorted Turbine Blades

Mon Nov 09, 2009 1:31 pm



Quoting B737200 (Thread starter):

Fan blades on many aircraft can be blended within manufactures limits. It also depends on what the blade is made of and how it's made.
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citationjet
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RE: Distorted Turbine Blades

Tue Nov 10, 2009 12:00 am

I doubt these blades can be blended.....

http://www.boreme.com/boreme/funny-2007/china-air-p1.php
.
Boeing Flown: 701,702,703;717;720;721,722;731,732,733,734,735,737,738,739;741,742,743,744,747SP;752,753;762,763;772,773.
 
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n901wa
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RE: Distorted Turbine Blades

Tue Nov 10, 2009 1:01 am

Wow, I didn't think N720JR was still on its gear. As a Kid my dad worked at Western and I flew on N93145 a lot on the comute between LAX and HNL, and I got to see it when it was being fitted out before it went to a Privte owner. I remember the Gold fixtures. The Last time I saw it was in the Avon Hanger in LAX. Kinda Glad its still around but, im sure not for long ( I hope im wrong)
As for the Blended blades Im not sure what the limits are, but I do have a set set of WAL B720B AMM on fish and I can try to look it up Limits. But I gotta find the tapes. (I found them in a Dumpster after the merger) .
Thanks for the info, brings back good memorys of WAL as a Kid. I was trying to find a Picture of 345 in better days, but I haven't converted all my dad's and my Photo's to Digital yet. Darren
 
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jetmech
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RE: Distorted Turbine Blades

Tue Nov 10, 2009 2:36 am



Quoting B737200 (Thread starter):
Anyone know what could have caused hem and can the plane safely fly with them?

As others have noted, the blades in the picture appear to have had the original damage blended out of them. If the original anomaly was able to be rectified to be within MM limits, it would have probably been reworked with the blades in situ by the line maintenance department. Provided the original damage is able to be dressed to the requirements of the MM, the blade will be safely able to remain in service. The damage is usually dressed with small files and emery paper.

Regards, JetMech
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B737200
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RE: Distorted Turbine Blades

Tue Nov 10, 2009 4:54 pm

As usual thanks guys, you're always very helpful.

Just one last question, am I right to assume that the damage was most likely caused by FOD but not by a catastrophic ingestion of something like a BIG bird? I would think the latter would have left more damage.

By the way anyone know of a website or such where I could find a record of incidents that happened to aircraft? If I remember correctly there was a link posted somewhere once, unless I'm imagining it.

Anyway once again thanks.
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fr8mech
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RE: Distorted Turbine Blades

Tue Nov 10, 2009 8:26 pm



Quoting B737200 (Reply 7):
Just one last question, am I right to assume that the damage was most likely caused by FOD but not by a catastrophic ingestion of something like a BIG bird? I would think the latter would have left more damage.

Usually, it is FOD, but a bird may cause the problem, depends on the size. The bigger the bird, the bigger the potential for damage. A bird strike does not destroy an engine. The USAir flight last winter was the exception, not the rule.
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B737200
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RE: Distorted Turbine Blades

Sat Nov 21, 2009 2:08 pm

Hey guys,

I am now well into my assignment but have come up with another query. Can anyone tell me what material the blades are made out of? I've been trying to find it on the Internet but to no avail. Any references will be welcome since it is for my assignment.

Thanks.
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jarheadk5
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RE: Distorted Turbine Blades

Sat Nov 21, 2009 7:43 pm



Quoting B737200 (Reply 9):
Can anyone tell me what material the blades are made out of?

Depends on the engine, and which blades you're speaking of.

Some newer turbofans, like the GE90 series, have composite fan blades; some older ones, like the CF6-50C2 have titanium fan blades.

Compressor blades can be titanium, steel, or "exotic" alloys like Inconel.

Power turbine blades are generally Inconel, Hastalloy, or some other exotic alloy (usually with a lot of nickel content) for heat resistance.

Some links:
http://www.haynesintl.com/HTAlloys.htm
http://www.steelforge.com/metaltidbits/inconel.htm
http://www.geae.com/ourcommitment/innovation/ge90fanblade.html

Wikipedia entries, while generally not a good sole-source of info, can be useful for finding actual references for some of the content.

Hope this helps; good luck with your report!
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747classic
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RE: Distorted Turbine Blades

Sat Nov 21, 2009 10:16 pm

I think the engines, mentioned in the thread starter are probably Pratt & Wittney JT3D-1 or -3 turbofan engines, as mounted on the B-720B.
So, the question is : from what material are these fan blades made ?
My guess is titanium, or a steel alloy, but I couldn't confirm it.
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B737200
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RE: Distorted Turbine Blades

Sun Nov 22, 2009 11:29 am



Quoting JarheadK5 (Reply 10):
Depends on the engine, and which blades you're speaking of.

Yes I was referring to the JT3D but I should have specified, my mistake.

Quoting 747classic (Reply 11):
My guess is titanium, or a steel alloy, but I couldn't confirm it.

I was thinking of titanium becuase I found a mention of it in an old FlightGlobal article on turbofans where the JT3D was mentioned, I however couldn't really confirm it.

I am quite surprised at the lack of information with regrads to this, seeing as the engine is nothing new and cutting edge.
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747classic
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RE: Distorted Turbine Blades

Sun Nov 22, 2009 6:00 pm

I found the following topic, about this subject : Hi-bypass Fan Blades: What Metal? (by Timz Jul 25 2008 in Tech Ops)

Peter.
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