Fan Blade numbering
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Fan Blade numbering
Is there a way to determine how mtc numbers the blades after they have been snagged for dings/dents? In our company, they used to number them with a marker after being snagged. They have stopped doing it. How do you know if #15 or #21 or whichever has been blended within limits, and there is a new ding?
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As MEL says there is a mark on the shaft adjacent to where the #1 blade goes. They are then numbered CW aft looking forward. So looking into the engine from the front anti-CW.
BTW. Do not assume numbers written on blades correspond to their position as per the AMM. The numbers may have been wriiten to aid blade removal and re-installation and may bear no relation to the actual blade number.
This convention applies to GE/RR etc there may of course be other numbering conventions for other types
BTW. Do not assume numbers written on blades correspond to their position as per the AMM. The numbers may have been wriiten to aid blade removal and re-installation and may bear no relation to the actual blade number.
This convention applies to GE/RR etc there may of course be other numbering conventions for other types
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BTW. Do not assume numbers written on blades correspond to their position as per the AMM. The numbers may have been wriiten to aid blade removal and re-installation and may bear no relation to the actual blade number.
On arrival, I was given the fan blade fitment sheet that the engine shop had found. The blades had been balanced on a rig at RR, and the fitting sequence bore no relation to the numbers. Me and 250 Pakistani passengers were not amused.
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I speak for RB211, as I am used to working on these. There is an asterisk on the fan hub where the N°1 blade goes. Then you number them in an anti clockwise direction when looking aft into the engine. Most of the time tere is an arrow next to the asterisk going ACW. The numbering is done before blade removal, so it will only stay the same when no blades are replaced (e.g. dirt removal of blade, lubrication, attrition liner repair...). When blades are replaced, engineers make a new distribution according to moment weights and they will have a paper like "blade 1 fits place 1; blade 2 fits place 3: blade 3 fits place 33,...
So as a pilot, ignore blade numbering.
Btw, numbering fan blades with an alcohol marker is a bad habit I often see. Not good on titanium blades. Better put painters tape on the blade and write on that.
As for your question, once a blade has been blended, it is seen as a serviceable one without limits. If there are limits, the blade will not be on that engine for long ( 1 or 2 flights). Any new dings will create a new situation which has to be looked up in the AMM. This manual states limits for multiple dings on one blade.
Swedish Steve, I had some similar incident. We got a wrong blade distribution faxed. When starting the engine afterwards for the check it was like the wing fell off with a very loud grinding noise, without even fully spooling up. Shutted down the engine and recalled the eicas page showing 5.9 units of vibration!
So as a pilot, ignore blade numbering.
Btw, numbering fan blades with an alcohol marker is a bad habit I often see. Not good on titanium blades. Better put painters tape on the blade and write on that.
As for your question, once a blade has been blended, it is seen as a serviceable one without limits. If there are limits, the blade will not be on that engine for long ( 1 or 2 flights). Any new dings will create a new situation which has to be looked up in the AMM. This manual states limits for multiple dings on one blade.
Swedish Steve, I had some similar incident. We got a wrong blade distribution faxed. When starting the engine afterwards for the check it was like the wing fell off with a very loud grinding noise, without even fully spooling up. Shutted down the engine and recalled the eicas page showing 5.9 units of vibration!
Last edited by Piper19; 28th Dec 2008 at 22:07.
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Well said everybody.
No1 blade on RB211 and Trents is marked with an asterisk on the disc next to the slot the blade slides into, then add a piece of masking tape to each blade at the outer end and mark the numbers as you rotate the fan around. Don't mark the blade direct as won't come off!
In the event of a full blade set change then the replacement set should come with a patternation chart, which allocates each replacement blade to a disc slot based on the weight characteristics of each blade - this is created using a special programme in the shop and should ensure that only a trim balance will be needed to balance the fan to AMM limits.
Also when changing blades, don't forget to immobilise the fan!
RBT
No1 blade on RB211 and Trents is marked with an asterisk on the disc next to the slot the blade slides into, then add a piece of masking tape to each blade at the outer end and mark the numbers as you rotate the fan around. Don't mark the blade direct as won't come off!
In the event of a full blade set change then the replacement set should come with a patternation chart, which allocates each replacement blade to a disc slot based on the weight characteristics of each blade - this is created using a special programme in the shop and should ensure that only a trim balance will be needed to balance the fan to AMM limits.
Also when changing blades, don't forget to immobilise the fan!
RBT
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Hello,
convention is blades are numbered as you would see them in 'rotation' as viewed from front looking aft, i.e. first blade to pass is #1, 2nd blade to pass is #2 etc. So for RR enignes with ACW rotation (when viewed from front) number in ACW direction. And North American engines with CW rotation (again when viewed from front) number in CW direction.
For Swedish Steve, it is most likely that you were sent with the engine shop distribution list. This document is where the blades are received for assy of the fan module in a box - with a piece of paper listing 1 - xx pn/sn. Then the blade weights are calculated and re-distributed by computer programme and a new list, or more commonly a new set of numbers are written in on the same sheet of paper next to the orignal 1 - xx numbers. I.e. #1 on original list may be now #14 position and #2 could be #8 and so on.
I have seen it happen a few times that blades have been fitted to the original 1 - xx blade order. This is not truly the fault of the line-engineer, as he would normally not refer to the shop document. The people who provide the list should 're-order' the blade positions on one list before sending out the work instruction.
For Dufo - RB211 data is generally IPS in the test-cell and converted to a/c units on-wing.
Regards,
N1 Vibes
convention is blades are numbered as you would see them in 'rotation' as viewed from front looking aft, i.e. first blade to pass is #1, 2nd blade to pass is #2 etc. So for RR enignes with ACW rotation (when viewed from front) number in ACW direction. And North American engines with CW rotation (again when viewed from front) number in CW direction.
For Swedish Steve, it is most likely that you were sent with the engine shop distribution list. This document is where the blades are received for assy of the fan module in a box - with a piece of paper listing 1 - xx pn/sn. Then the blade weights are calculated and re-distributed by computer programme and a new list, or more commonly a new set of numbers are written in on the same sheet of paper next to the orignal 1 - xx numbers. I.e. #1 on original list may be now #14 position and #2 could be #8 and so on.
I have seen it happen a few times that blades have been fitted to the original 1 - xx blade order. This is not truly the fault of the line-engineer, as he would normally not refer to the shop document. The people who provide the list should 're-order' the blade positions on one list before sending out the work instruction.
For Dufo - RB211 data is generally IPS in the test-cell and converted to a/c units on-wing.
Regards,
N1 Vibes
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Thanks for all the informative replies. Can you see the asteiric on the hub from standing on the ground during a normal walk around inspection, or do you have to be standing right in the cowl? My eyesight isn't what it used to be!!
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319/320...Chances are you probably wont see from the ground (well depends on the a/c type)...If you can get into the fan inlet then its no problem finding it. Some engines have the little dimple colored white for ease of identification. The CF6 engine on the 330..you would definately need to climb into the inlet cowl and find the identification mark
319/320
With the CFM series powerplants which i assume my be fitted to your a/c there is not a asterix but rather a small circle indicating the first blade position. It is easy enough to see.
With the CFM series powerplants which i assume my be fitted to your a/c there is not a asterix but rather a small circle indicating the first blade position. It is easy enough to see.
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....the fan could be windmilling, or the asterisk may be at the top of the rotor, not the bottom where you can see it from the ground and I don't think you can count that qucikly or accurately. For the purpose of precisely identifying a blade - getting in the cowl is much better......
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As an outsider I would have expected each blade to have had a serial number and a log kept of which SN was used in each position. Isn't it like that? What happens when an engine is wrecked, do they have to figure out which blade was where from the damage alone?
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The Fan Blade Part Number, Serial Number and Moment Weight are actually laser etched into the blade but its actually in the root section where they attach/slot into the hub. These are recorded at certain intervals...i.e. the likes of a heavy overhaul check where fan blades would be removed from the engine for insection, lubrication etc.
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Ok, thanks again. It's a RR Trent engine. I'm guessing the asterik is under the hub? Just how bad is it for the titanium blades if you mark them with a sharpie? That must be why they don't do it anymore.
Ok, thanks again. It's a RR Trent engine. I'm guessing the asterik is under the hub? Just how bad is it for the titanium blades if you mark them with a sharpie? That must be why they don't do it anymore
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Indeed as said, at the (invisible) blade root there is the SN, moment weight and overhaul number, which states how many times the blade has been reworked. Each blade is logged as they have a finite lifetime etc...