737tdi From United States of America, joined Sep 2007, 466 posts, RR: 0 Reply 1, posted (5 years 6 months 3 days 23 hours ago) and read 4968 times:
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.
Mender From United Kingdom, joined Feb 2004, 224 posts, RR: 0 Reply 2, posted (5 years 6 months 3 days 23 hours ago) and read 4964 times:
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 From United States of America, joined Sep 2007, 466 posts, RR: 0 Reply 3, posted (5 years 6 months 3 days 22 hours ago) and read 4942 times:
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.
JetMech From Australia, joined Mar 2006, 2588 posts, RR: 53 Reply 4, posted (5 years 6 months 3 days 21 hours ago) and read 4917 times:
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
JetMech split the back of his pants. He can feel the wind in his hair.
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 5, posted (5 years 6 months 3 days 16 hours ago) and read 4844 times:
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
Mender From United Kingdom, joined Feb 2004, 224 posts, RR: 0 Reply 7, posted (5 years 6 months 2 days 12 hours ago) and read 4659 times:
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.
Mender From United Kingdom, joined Feb 2004, 224 posts, RR: 0 Reply 9, posted (5 years 5 months 3 weeks 6 days 15 hours ago) and read 4371 times:
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 From United States of America, joined Jul 2006, 214 posts, RR: 25 Reply 10, posted (5 years 5 months 3 weeks 6 days 9 hours ago) and read 4338 times:
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 ).
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.
Mender From United Kingdom, joined Feb 2004, 224 posts, RR: 0 Reply 12, posted (5 years 5 months 3 weeks 6 days 1 hour ago) and read 4305 times:
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 From United States of America, joined Jul 2006, 214 posts, RR: 25 Reply 13, posted (5 years 5 months 3 weeks 5 days 16 hours ago) and read 4266 times:
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.
HAWK21M From India, joined Jan 2001, 31201 posts, RR: 58 Reply 14, posted (4 years 4 months 2 weeks 2 days 5 hours ago) and read 3784 times:
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?
Ex52tech From United States of America, joined Dec 2006, 559 posts, RR: 1 Reply 15, posted (4 years 4 months 2 weeks 1 day 20 hours ago) and read 3709 times:
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 From United Kingdom, joined Feb 2004, 224 posts, RR: 0 Reply 16, posted (4 years 4 months 2 weeks 1 day 17 hours ago) and read 3668 times:
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?
MarkC From United States of America, joined Apr 2006, 259 posts, RR: 0 Reply 17, posted (4 years 4 months 2 weeks 1 day 11 hours ago) and read 3609 times:
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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