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HAWK21M
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Markings On Fan Blade Surface.

Sat Nov 24, 2007 9:44 am

What does a circle and/or triangle inked mark on each Fan blade of a Turbofan Engine signify.
Anyone aware.
regds
MEL

[Edited 2007-11-24 01:46:15]
I may not win often, but I damn well never lose!!! ;)
 
737tdi
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RE: Markings On Fan Blade Surface.

Sat Nov 24, 2007 12:28 pm

Hawk: Did you notice this on a particular operators engines? We mark our fan blades but they are simply numbered to identify location to maintain fan balance. Don't really know why they would be marked with circles/triangles though. Most likely a code for the mechanics. Sorry I couldn't help more.

737tdi
 
Mender
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RE: Markings On Fan Blade Surface.

Sat Nov 24, 2007 12:39 pm

Aerodynamic standard or Mod state of the rotor blades.

"The changed aerodynamic standard of rotor blades post RR SB72-C946 can be identified by a blue triangle on the suction surface of the rotor blade." AMM 72-31-13 Page 402
 
737tdi
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RE: Markings On Fan Blade Surface.

Sat Nov 24, 2007 1:20 pm

Mender: I would think Mod. status would be etched into the blade root along with the blade weight instead of a marker. I know we have to renumber our blades from time to time due to fading of the ink. You could definately be right though with RR, just doesn't seem very permanent which it definately should be.
 
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jetmech
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RE: Markings On Fan Blade Surface.

Sat Nov 24, 2007 2:24 pm



Quoting HAWK21M (Thread starter):
What does a circle and/or triangle inked mark on each Fan blade of a Turbofan Engine signify.

I've seen those markings as well, but I don't recall if it was on a G2 or a T-700. I'd say it was on the T-700. I'd say Tepidhalibut or Manzoori would know

Regards, JetMech
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HAWK21M
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RE: Markings On Fan Blade Surface.

Sat Nov 24, 2007 7:25 pm



Quoting 737tdi (Reply 1):
Did you notice this on a particular operators engines

Yes.The RB211-535E4

Quoting Mender (Reply 2):
The changed aerodynamic standard of rotor blades post RR SB72-C946 can be identified by a blue triangle on the suction surface of the rotor blade." AMM 72-31-13 Page 402

I'll check this out at work.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
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IFixPlanes
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RE: Markings On Fan Blade Surface.

Sun Nov 25, 2007 7:41 pm

never tell an engineer he is wrong ;-)
 
Mender
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RE: Markings On Fan Blade Surface.

Sun Nov 25, 2007 11:11 pm

Thanks for that IFixPlanes.

This is a direct copy & paste of the AMM 72-31-13 para 1 General, sub para L. It doesn't mention the fan blade lube.

L. Aerodynamic identification of the rotor blades is as follows:
(1) The initial aerodynamic standard of rotor blades post RR SB 72-8354 and RR SB 72-9132 can be identified a white paint mark on the blade root.
(2) The changed aerodynamic standard of rotor blades post RR SB 72-8342 can be identified by a gold paint mark on the blade root.
(3) The changed aerodynamic standard of rotor blades post RR SB 72-9513 can be identified by a sea green paint mark on the blade root.
(4) The changed aerodynamic standard of rotor blades post RR SB72-C946 can be identified by a blue triangle on the suction surface of the rotor blade.
 
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HAWK21M
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RE: Markings On Fan Blade Surface.

Tue Nov 27, 2007 5:42 pm



Quoting IFixPlanes (Reply 6):

Thanks for the Triangle explanation what about the circle.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Mender
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RE: Markings On Fan Blade Surface.

Fri Nov 30, 2007 8:51 pm

Sorry, been too busy to reply..........

The circle or spot shows the fan blade post Rolls Royce SB RB211-72-C138

A revised LP compressor blade is introduced identical to the existing item in terms of external and aerodynamic shape but incorporating the following changes.
(i) The airfoil panels are manufactured from a revised material specification (unidirectionally rolled titanium plate) having greater resistance to crack propagation.
(ii) The manufacturing process has been revised to promote the growth of a modified surface layer on internal surfaces preventing micro-crack initiation.
(iii) A chemically etched 25 mm. (1.00in.) diameter blue spot is added to the suction surface, close to the leading edge tip. This is to enable easy identification of blades for on-wing transient acoustic pressure (T.A.P.) test purposes when installed on the aircraft.
 
jetlife2
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RE: Markings On Fan Blade Surface.

Sat Dec 01, 2007 2:09 am

Interesting stuff.

It brings to mind a process question:

Is it considered OK to directly quote/reproduce AMM or SB language here?

I used to work for A Big Jet Engine Company, Ltd. Then 20+ yrs ago I moved, and now I work for A Really Huge Jet Engine Company, Inc. (names changed  Smile ).

Neither my former employer or present one would be thrilled to see this kind of data here. With nearly 30 yrs in jet engines engineering (yes I am getting old!) I can learn quite a bit from this thread - on such subjects as fan blade root lubrication, hollow titanium manufacturing, on wing TAP testing, management of fan aero configurations...maybe not apparent to all, but in the right hands this is good stuff. Not quite 2+2 = 4, more like you just gave me 1 and I already knew 3. A few "ahas!" popped into my head.

It may seem like a meaningless formality if you are in the business and read manuals and SB's all day long, it can seem like this is data that everyone has, but it's really not the case.

My 2 cents, I would be interested in others' opinions.

GHR
My views are not necessarily the views of the GE Company
 
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HAWK21M
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RE: Markings On Fan Blade Surface.

Sat Dec 01, 2007 7:38 am



Quoting Jetlife2 (Reply 10):
Neither my former employer or present one would be thrilled to see this kind of data here

On the contarary.Discussion based on knowledge acquired with no word to word replicating should not be a source of concern.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Mender
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RE: Markings On Fan Blade Surface.

Sat Dec 01, 2007 10:16 am



Quoting Jetlife2 (Reply 10):

Neither my former employer or present one would be thrilled to see this kind of data here.

You may well be right but personally I can't see the harm in posting a few lines giving a general overview from a lengthy document. I've not quoted any materials specifications or instructions to accomplish anything, nor would I.

I liken what I've posted to quoting the ingredients from the back of a Coke can or the ingredients to a KFC. I've not like given the recipe reproduce the Coke or the KFC. That said I wouldn't post a scan of a document or copy & paste the full text.
 
jetlife2
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RE: Markings On Fan Blade Surface.

Sat Dec 01, 2007 7:46 pm



Quoting HAWK21M (Reply 11):
On the contarary.Discussion based on knowledge acquired with no word to word replicating should not be a source of concern.

I completely agree with you on this approach - but what was posted here was just that, replicated word for word, and even scanned out of the manual. That's what got my attention.
My views are not necessarily the views of the GE Company
 
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HAWK21M
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RE: Markings On Fan Blade Surface.

Sat Jan 10, 2009 6:38 am

Noticed an RB211-535E4 recently with only "One" blade having the dark blue circle,the rest did not.
Could this be a possibility that that one blade was replaced recently hence had the inspection done?

regds
MEL.
I may not win often, but I damn well never lose!!! ;)
 
ex52tech
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RE: Markings On Fan Blade Surface.

Sat Jan 10, 2009 3:57 pm



Quoting 737tdi (Reply 3):
I would think Mod. status would be etched into the blade root along with the blade weight instead of a marker.

Mod status would be ok to etch into the blade root, but the weighted moment would change with erosion or damage repair. That is why they are stamped instead of eteched, you only need to know when you are replacing matched sets of blades to maintain balance.

Quoting Jetlife2 (Reply 10):
Is it considered OK to directly quote/reproduce AMM or SB language here?



Quoting Jetlife2 (Reply 10):
Neither my former employer or present one would be thrilled to see this kind of data here.

I would rather see the actual written material, if it was that easy to post it here than those......"sectets".......got out along time ago.
"Saddest thing I ever witnessed....an airplane being scrapped"
 
Mender
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RE: Markings On Fan Blade Surface.

Sat Jan 10, 2009 6:33 pm



Quoting HAWK21M (Reply 14):
Noticed an RB211-535E4 recently with only "One" blade having the dark blue circle,the rest did not.
Could this be a possibility that that one blade was replaced recently hence had the inspection done?

Yes.
 
MarkC
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RE: Markings On Fan Blade Surface.

Sun Jan 11, 2009 12:13 am



Quoting Jetlife2 (Reply 10):
Is it considered OK to directly quote/reproduce AMM or SB language here?

I hear you on this, and I am always surprised to find this sort of thing.

I have had many discussions with laywers on this subject. I would be subject to dismissial if I did something such as post or transmit actual pages from the engine manuals or SB's or whatever publication. Companies who purchase these documents do so under a non-disclosure agreement with RR, GE, PW, or whoever. They are absolutely not in the public domain.

To paraphrase generalities is a bit grayer, and is probably acceptable.

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