Jet Tech : Turbine Blade Inspection
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- เผยแพร่เมื่อ 14 ม.ค. 2012
- A detailed demonstration of the first step in the process of determining if a turbine blade removed from an engine is suitable for further service.
The visual inspection requires very little preparation of the part, and is used to quickly "weed out" the parts that are obviously damaged.
This saves the resources that would be wasted by sending them through dye penetrant Non Destructive Testing. - ยานยนต์และพาหนะ
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These videos of yours are so interesting.I work as an auto mechanic and have seen the insides of many internal combustion engines, but to see the insides of a jet engine is like looking at some kind of alien technology.Hats off to you for posting these videos and helping me to be just a little smarter.
It never ceases to amaze me how something so complex made of so many tiny parts doesn't shred itself within a few minutes of running at full power. Love these videos. Keep 'em coming :)
Jay, great thanks from Belgium for the clarification about the clearance's difference between the industrial and the airline engine. Cheers
There is something very impressive about that turbine blade, the power, the speed, the temperature,and the intensity of thought embedded in that chunk of metal. I feel good to have all that shared with me, thank you.
Anyone who wants to know why jet engines are so expensive need only watch this video! The cutaway turbine blade is very impressive! Do you know if it's cast/forged in one piece, and if so, how the heck do they put all those holes in there?Nickle eating termites? You are now my new favorite channel!
Awesome Channel, all my questions are being answered on this channel, despite high-end vids explaining how it works, but now showing how.
This is awesome stuff, keep it up!
Thank you for explanation! It is so intresting to watch these videos. I always wanted to see how a jet engine looks like and what steps are necessary for inspection and the tricks an experienced engineer like you can give! I love it!
@TheIndustrialphreak Turbine blades don't suffer impact damage from sand, because most of it gets centrifuged out of the airstream in the compressor, and whatever dust is left gets melted in the combustors.
Sand damage to turbine blades is a deposit of melted glass-like material.
Since the glass is harder than the alloy the blades are made of, they are usually scrapped.
Sorry , Saxonlight... I deleted your comment trying to correct a spelling mistake in my answer to it:
We require a 30% deposit. Our company is different, because we never exceed our quote. If we discover unexpected problems after quoting a price, we solve them at our own cost.
The engines we deal with are shipped to us whole.
Many of the operators we work for treat their engines as black boxes. All engine work takes place in our shop,
We don't work on newer commercial aircraft engines
Sir you have posted this video on 2012.. And here watching this video 2024👀..
Looking at the cutaway and how fine the details are, it truly is amazing how they make them. One can understand all of the fuss about volcanic ash a few years ago too!
@AgentJayZ No worries AJZ. =) Thanks for taking the time to answer. I continue to be fascinated by your videos and the technology featured in them.
Hi, I want to thank you for all expierence sent to all of us. Repair of these engines take a lot of caution.
hi sir great to come across your channel. I'm about to start my new job as a CNC trainee for a well recognized aero space company and I feel fortunate enough to 1 be employed and to start learning the tricks of the trade from your channel and hope to see more of your videos soon thanks for sharing
Great vid. A while ago, I saw a Rolls Royce vid that shows the manufacture of these air cooled blades and guide vanes - Amazing tech. Probably the most sophisticated part of manufacturing an engine. Don't know how GE do it, but Rolls have a 'craft department' comprised of middle aged women who make the wax molds by hand. Amazing to think that most of these blades are formed from a single metal crystal.
Great explanation!
This is fascinating technology that should be shown in schools. First of all the principles of the compressor blade design and why there is no blow back into the compressor and the hot gas leaves through the turbine, That alone needs a good understanding of diffusers to slow down the air, to increase pressure and sustain the flame,
The manufacturing of the turbine blades is a miracle of engineering and I am appreciating the experience of this gentleman at his calmness to work on such a machine where there is so much responsibility, It is a miracle that that he sleeps at all for it would worry me to think that I left something lose in the works.
Congratulations on your courage to handle such complexity and such high responsibilities both in a financial sense , engineering sense and human life sense.
Not an easy situation ,
I love the cut away. I just saw another cutaway turbine blade at the Pima Air and Space Museum. I'm sure that if I hadn't seen your videos I would have been less impressed with it when I saw it.
Typically several thousand hours to overhaul an industrial gas turbine. I don't have experience with modern airliner engines, but I would guess they would require more.
I think most airlines contract their engine work out to shops like MTU, which is so much larger a corporation than our little shop that a comparison can't really be made.
@drewbin101 The industrial blades sent to us for evaluation were in terrible shape. I hope I can clear things up a bit by mentioning the aircraft and industrial turbine blades are identical when new. They have the same part number. Industrial engines often have higher temp limits and run much longer than aircraft engines, but their throttles are changed very slowly, which lessens the stress causes by temp changes.
Rapid power changes are tough on turbines.
@Xandr128 Yes, I'm not saying that all industrial engines seize on emergency shutdown, just that it is more likely than it would be with an aircraft flameout.
@xxJohn1977xx there are very few "pairings" of engines that exist both as flight and industrial versions, and it is those cases only where a direct comparison can be made. With that in mind, either of the options you mention are possible. The difference we're talking about is 30 - 50 thousandths of an inch. There are series of blades of different lengths, and there are different tip-shroud inserts of different thickness.
thank you for the details.
@mytmousemalibu GE tends to favor the VSV system, because I think they invented it with the J79.
RR likes to use bleed valves.
Both systems only purpose is to avoid compressor stalls while transitioning from idle to full power.
Both also have their pros and cons.
@Morkvonork Similar to that. Newer alloys are always being developed, and are even better than Inconel.
13:34 "The condition of these blades would be ... uhm... the technical term is ... garbage."
absolutely made my day :-) Thank you!
@jkkshjr I think one of the methods used is electromachining, where a wire is used as an electrode for small discharges to slowly eat away at the metal in the blade. Very precise and doesn't make a lot of heat (no thermal stress) but very slow and therefor expensive.
@elghian We just bought 5 of the pairs, in nice shape, but used and certified. We paid about 2K per pair. That's a little less than 50% of replacement.
the idea of having to check every one of those little cooling holes on each blade scares me , would go insane , or get a massive headache XD
@lexichronicle2 We don't have either machine at this time, and I think both would be useful in this case.
Great videos !! I just can't get over touching the parts by hand with no gloves 😮 in production it's a big no no but your rehabbing used engines not new,, once again great videos
Particularly interesting.
Very interesting and informative 👍👍👍👌
It's an engine shop; you'll find metal chips everywhere. I was using a black rag as a background, because the camera seemed to prefer that. And black shows everything...
Some times, when we need immediately start after emergenecy shutdown we do crank for 15 minutes. Not later that 10 minutes after shutdown)
Great video, thanks!
WELL EXPLAINED..
Brutus Buckeye (last 30 sec, sticker on cabinet) helping everyone in the shop? Go Bucks!
Firstly, thanks A LOT for the time, effort and quality of these videos! I'm a tech guy and love this kind of detailed information. I was wondering - approximately how many man-hours are involved in a "typical" engine rebuild? Do airlines utilize their own mechanics for engine repair or do they send them out to shops like yours?
thanks for your fantastic videos. How do they manifacture thoose blades with tiny air holes ?
@lexichronicle2 Yup, thats the one. Great vid. I also recommend it.
It varies from airline to airline and even aircraft to aircraft. At my particular airline on my aircraft we actually lease the engines from GE. Our mechanics will do most of the work on the accessories minor repairs on the engine itself but most of the major inspections and overhauls are done by GE.
I'll have to try and draw a picture of this in one of my Questions videos... hang on.
Mostly the shroud material wears, so when the gap gets too big, you replace the shroud.
Superb vid! On the issue of cleaning a blade pair. I understand why glass beading would be a bad idea, has S&S thought about using baking soda? I have seen it used in the cleaning of steam turbine systems for power production, but not in the turbine itself.
Damm, now i want find out how those blades with cooling channels have been made.
thankes very match for you time
@cheetawolf There are people selling junk blades on Ebay, so you could make your own cutaway.
Hello Sir, thank you for providing us al these great info. I have Question, what is the type of material that coat jet eng combustion Chamber and the liner?
What do you suggest that process for ?
@Lea71777 No... I've never seen nick-nacks capitalized
I think I saw three (maybe four) holes on the blades' bottom surface under the fir tree. Once the blades are installed on the disk, How does air get to those holes? I think I understand the flow up the inside and onto the surface. I just can't visualize how air gets into those bottom blade holes.
Hey Jay,
Love the Vids and channel much! I was wondering about the comment you made about the tolerances in blade placement and clearance! Does this in effect mean that airline engines are in a sense purposely made to be slightly inefficient to allow for failsafe measures? And i was wondering with your experience and hands on maintenance of these types of engines, it seems that airline engines unlike industrial engines are never really "broken in" or ever reach their maximum limits? thoughts?
How do they make such a fine blade?
I know this is an older video, but I had an idea: for checking if any of the really long thin channels are blocked, is a liwuid ever pumped through the blade to look for blocked holes or restrictions?
For some reason this video made me feel cold. I had to put a coat on.
hello jayz,when l used to work in the R/D casting Dept at the ,El Sacondo,Cal plant at garret aeroserch, l asked if they use hydrachloric aced to clean the in side out ? they said no ,only high presser water and time.P,s, save the old blades as they are very expensive and have a lot of colambinn nickal cromem and other googys.bye for now
Very nice and interesting video indeed! I had some thoughts tho, in the first demonstration you showed us a ceramic coated blade, which could endure more heat. The other pair of blade (those which came apart) where air cooled to endure more heat, but what if you coated them with ceramic as well (+ being air cooled)? Wouldn't they withstand yet more heat then? Second though is regarding those small holes. Are there any specific procedure to really make sure those small passages aren't clogged other than the visual inspection?
+SuburbAllied Yes, and Yes. You can use air or water flow to determine whether a hole is blocked, but it's usually visible on inspection.
just a little aside, I was distracted by the background noise...was it a gale or something?
Congratulations on the videos, I am completely hooked on them!
Can you explain why the width of Fir Tree is different for the Blade pair. Thanks.
Hey Jay just had a question @2:57 when you are inspecting for wear in the fir-tree portion , does the blade move when it is installed or is there some allowable movement, also I am guessing as the turbine blade is quite hot how does the fir-tree accommodate the thermal expansion
@drewbin101 Well, let's not be callin' the aero engines "inefficient". Depends on your point of view. Aero people might call industrial engines "a little too tight for safety".
And aero engines are just right on the first day, so no need to break anything in. They also are maintained preventatively ( intensely so), so they are not ever as "worn out" when they go for overhaul as an industrial engine might get.
Apples and oranges.. can't really compare...
Amazing shit 😍👍🏽 🔎
So i found myself wondering if you might have some normal deteriorated turbine blades to show off? At the school which I attended, we had lots of dirty old turbine blades, seriously grungy. Good examples of burned up or otherwise mechanicaly damaged parts by some means. That or all evidence erase from bead blasting.
Cont.....
Well considering the wear that the Industrial engine appears to show in the video, compared to the CF-6 blades, i'm not sure of the lifespan of each in comparison, but the industrial blades appeared be much more worn.You also mentioned during the video that the industrial engines are run much hotter, i'm assuming that even with proper maintenance, the engines seem to be taking on a lot of abuse! So my comparison was aimed at the differences, giving the use of essentially the same core? thanks..
How do you set distance between blades and shroud?
How did they made air cooling hole inside the blades because very small to drills by cnc machines can i know please ?
When you guys repair an engine someone has sent in, then have to replace blades and other expensive parts during the process. How are those types of extra costs handled? For example do you quote a customer X for the basic repair then at the end of the job add on Y for replacement parts? Does the customer have to put a % down before the project starts?
you mentioned you cannot media blast the blades because of the tiny holes and cavities, perhaps CO2 (dry ice) blasting... it shouldn't damage the holes or get stuck in the channels (dry ice turns to gas upon surface contact.)
Are you still using Pt-based ceramic coatings on the blades?I have not processed any "white" ceramic, and how do you choose your brazing?I understand that Ni-based braze are used in the less demanding positions.I wish I could source more of your trash.
Just one question what dose a set of blades damaged by abrasives such as sand look like?
Jay, is GE the most prevelent user of VGV's, never seen them anywhwere else. Sounds like an advantagous feature minus the added cost and complexity. Do they also improve throttling and help against stalls/surge? No further NDI besides dye?
Its interesting that these high temperature blades are held together by brazing. I would guess it is a special type brazing material, and that the heat sinking capability of the rotor keeps the brazing material cool enough to keep the blades together. (not to mention the mechanical ties)
Can you elaborate on this a bit please ???\
Thanks
It's called furnace brazing, and is a high temp process that I don't know much about. The disc is cooled and does act as a heat sink for the blades. Very observant of you. Many folks don't get that.
Hi Jay, got a question - The damage that you have shown in the vid, how old or how long has these blades been in operation on the engine, since their last inspection, and how long does a typical engine stay in service before being stripped/inspected?
And Lastly, How is balancing done for the engine, as an unbalanced shaft would rip it self apart?
Keep the vids coming!
Werner Brits The heat damage could have occurred in seconds, depending how hot things got.
It varies from engine type to engine type.
A shaft won't rip itself apart.
Got videos on balancing.
Doesn't Turbine blades need a x-Ray inspection to check the impurities in the blade internal passages?
What form of CF-6 is this? A 80 or a 50?
Are they made of Inconel?
What do you do with inconel/etc. parts that completely fail inspection and aren't economically repairable? Sell them as scrap? eBay them as desk toys/collectibles?
Recycle them. Sometimes trade for cool stuff. Never sell.
Beautiful engineering, They look expensive, how much does just one of these blades cost.
New, several thousand.
Hi AgentJayZ I follow your channel with interest and everything you expose is clear beyond any doubt. But now rises a question on my little italian mind. Is the air cooling the turbine blades trough the holes to a higher pressure respect the hot gases coming from the combustor? And if it is so where it is coming from?
thanks
Daniele
Air will only move from an area of higher pressure to an area of lower pressure, without exception anywhere in the known universe.
Usually turbine cooling air is HP compressor bleed air.
The pathways for the air are composed of the spaces between components, so are difficult to illustrate of show on video, but I have done it a few times.
So basically the pressure present in HP compressor at the spill point is somewhat higher than the pressure present in the gas flow before the turbine wheel? Sorry to bother you again but it is really interesting.... :-)
Yes.
I don't know what a spill point is, but we review the pressure at each point in a turbojet engine in my series of videos called
Diagrams...
Sorry I don't own the correct terminology. Spill point may be the compressor stage at which air is picked up to cool the turbine blades.
thank you very much. I ville rewiew the "Diagrams series"
Is ultrasonic cleaning a viable option? with all the intricate cooling holes etc
Rancid Cocks Yes, it is one of the methods we use.
I would think you guys would have to wear uniforms. It looks kinda casual around there to me.
Are turbine airfoils made from inconel or udimet-500?
The alloys are always changing, getting better and better.
how often are the blades supposed to be inspected?
It depends on the engine model.
The older engines I work on have blade inspectionintervals between 100 and 400 hours.
Modern engines usually specify a number of cycles instead of running hours.
Do you work on just GE engines? P&W call the turbine cases BOAS, Blade Outer Air Seals
If I may ask a humble question. What kind of work pants are you wearing in this video?
Stiff
is there a video on abradable blade tips?
I have not featured those yet, because almost all compressor blades these days have what are sometimes called squealer tips.
Sort of like radial tires on cars, it's an idea that has been universally adopted.
I'll demonstrate in a vid when I can find a non-squealer tip blade.
AgentJayZ Thanks. I enjoy and appreciate your videos. They are well engineered.
3:57-3:58 suddendly you see a metal grain lying on the workdesk....
Those blades with thru holes look like they get clogged easily. Does this happen often
It does not happen often. The cooling air originates from sources near the central axis of a high speed rotating assembly.
Are those 'always' matched pairs? Or can they be unbrazed and mix and match?
There's no need to break them apart. Also, that would require they be welded or furnace brazed together.
. So we didnt really have any good examples of normal stages of wear from mild-pretty bad. Things like plasma coating loss, blistering, stress-ruptures, sulfidation, etc. Perhaps a short-coming of our institute to lack these things, we can't have it all. Crappy pictures in books and descriptions only go so far. Much better to see these things first hand and wondered if you might have some examples to photo or even consider a video on the topic?
13:55 A display piece.
12:19 😆😆🤣🤣 Good point.
What is the approximate G force on an average turbine blade tip.. at maximum power..
30 inches in diameter at the tips. Max rpm is a nominal 7200. That data, combined with a few seconds on Google, and there you are !
similar RPM to a Hard Drive...
the small rc jet turbines would it be possible to build one in my shop at home I have a small foundry metal lathe and milling machine do you know I web site I can go to for info thanks .
If you want to do a good job of it, I would not follow anyone else's plan. There is a great deal of engineering involved, so many people start with an automotive turbocharger and modify it.
The more you study the design of real engines, the more successful you will be.
There are many people out there who claim to have built jet engines, but really have created dangerous noise-making toys.
I wish you luck!
is there a design of an engine , that you would recommend the study of ,for an ultralight... ?
and thank you for your time .
what about CO2 blasting?
So ... If I am looking at purchasing a Turbine Legend with a Walter 601D, with allegedly a 300 hour clean bore scope report, yielding a clean report, should I continue, or am I a complete fool for considering a Walter engine in the first place ?
I have no knowledge or experience with that engine. One of my pals tried a Walter 701 in (on!) a Toyota truck...
Have a look at powermodz jet truck...
Makes me wish the navy would've let me have pictures of when we had a PT Nozzle failure in one of our LM2500, the PT vibed out and wore out the Nozzle dovetail causing the Nozzles to sit on the rotor disk. That was a funny picture on the scope
I have a problem in my PW121 engine during a boroscope inspection I found on the HP turbine vane separation between one set is recomended removed the engine
Is there anyone who watching this video on 2024?
what about CO2 blasting?