Perils of Cylinder Work
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- čas přidán 21. 11. 2016
- Maintenance expert Mike Busch digs into the thorny issue of tightening critical fasteners properly when installing cylinders on a piston aircraft engine, he explains why it is so difficult to get it right when doing it with the engine still mounted. Savvy Aviation offers Professional Maintenance Services to owners of General Aviation aircraft, such as: Savvy Mx (Professional Maintenance Management), Savvy QA (Expert Consulting), Savvy Prebuy, SavvyAnalysis (Engine Data Analysis) and Savvy Breakdown Assistance. For more info see savvyaviation.com and www.sportys.com/pilotshop/spor.... This channel offers videos about those services, and webinars hosted by Mike Busch which were produced by the Experimental Aircraft Association (EAA) and sponsored by Aircraft Spruce and Specialty
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I am usually afraid of webinars or zoom discussion because of bad audio qualities, associated with people without the skills to do it well. (Taking into account the delays etc.) but here I must say this was very well done. It was a real pleasure to hear Mr Busch who was very articulate in his speech.
Ok, as a pilot who flies an iO 550, I now have a lot more to worry about. Good video. From now on, my mechanic flies with me the first flight after cylinder work, lol. Its like when I go to the dentist, and he is getting ready to drill, I put my hand around his jewels and simply say, now we aren't going to hurt each other are we.
🤣😂😆
As a car maniac, I really enjoy these webinars, so much more science and material knowledge than the typical rule of thumb and even halfbaked approach to a lot of car engine maintenance issues.
Many thanks. Great info, just as relevant for vehicle and boat engines etc. I have worked on VW and Citroen air cooled engines over the years, and this video should be mandatory watching. Regards from London UK.
I wish I had seen your video 6 years ago. I found all this in hard way. The damage to our continental io-360ES was exactly what you are describing, crank case and damage to the crank shaft caused by moving bearing on cylinder no 4. We ended up buying an exchanged zero timed engine from continental.
I also found your book on maintenance very realistic and true.
Passing on your knowledge and experience is geatly appreciated.
God bless.
I knew the pilot/mechanic pretty well on N434M. It was a sad day when he crashed, even had a PAX that was in the same Army unit along with him. I never knew him to take short cuts and he was a experienced mechanic and pilot who was trusted by many to perform work on their aircraft. Just goes to show that no matter how good you think you are, it just takes one screw up to reach out and bite you. He worked on a LOT of aircraft at VGT, I never heard but I imagine there were some reinspections after the accident.
And this is why it's worth getting someone like Mattituck to put it together, I was a corp duster and I loved my Lycoming io540. This engine saw me through many hundreds of hours in Africa , we did have an ex RAF engineer to look after them and he was the best, a guy called Pete Ashmore . I find this type of video so interesting, you learn so much.
I love this video, thank you. Your discussion of fastener torque, wet vs dry preloading was fascinating. Why this isn't taught more widely is beyond me. I learned quite a bit with this hour. Thanks again.
I'm a high performance automotive hobbyist, ARP Bolts broadcasts loud and clear everywhere, the crucial importance of proper fastener lubrication, both the threads and under the head.
Pretty much every engine building book I've ever read also covers the same stuff.
I was always told that aircraft mechanics are the ultimate, that they adhere to the strictest standards because failure has such high risk of being fatal.
I'm absolutely astounded and flabbergasted to hear that there would be any aircraft mechanic not properly torquing their cylinder head bolts. How is that even possible? Are there really DIY backyard aircraft mechanics?
@@Syclone0044 Apologies. I'm an amateur, not even close to being a pro. Fear not, you're safe: I promise never to touch an aircraft you'll ever board :-) I understand the same as you do about A&Ps, have known many over the years ... we just never talked about how to torque fasteners :-)
Same here, and to learn that one of the 2 big manufacturer doesn't even offer torque plate ? @@Syclone0044
These types of guys have so much information. Invaluable.
Exactly right, very good video about how to do it properly. Nice work.
I've never had any issues changing cylinders (done hundreds of these) but I've been trained correctly and always rtfm !
Excellent information!
I'm not an A&P but I am a 25year veteran Mercedes Benz and just about everything else mechanic, and the torque wrench and bolt stretching and improper torque issue is a real issue!
This blows my mind I worked for several years for a shop that restored vintage Italian race cars and the owner of the shop andmy father who worked there were very meticulous and I kind of thought that most of this was all common knowledge but in the world in which we live today where nothing is repaired anymore the people that would pass on this knowledge to younger people just aren't there anymore.To anybody with real mechanical ability these are pretty basic skills but when I look around it amazes me how many people just don't understand because this knowledge is not being passed down anymore. The days of using anti seize and molybdenum disulfide to lubricate threads has been replaced mechanics who don't want to get dirty, and quick use spray oil out of cans that do literally not much more than stop squeaking I will agree 100% with everything this guy is saying because I can't tell you how many times I've repaired threads for people who didn't put any anti seize or oil or anything on them and destroyed them and when you questioned them they tell you they didn't want to get anti seize on their hands cuz it doesn't wash off easily this is the price we're going to pay for having cars and other large things that we used to fix being made in a non serviceable fashion you lose all the service people when you lose the service people you eventually lose the knowledge. basic rule of thumb don't ever put any Fastener together ever dry a good mechanic can repeat things that he's been shown a great mechanic uses all the knowledge he's learned in other places and applies it to everything he does and thinks about everything he's doing and how these other things will play into what he's doing at present time unfortunately I would be willing to bet the story about the cylinder that came off that caused that crash I'm sure the man just simply forgot to tighten those Fasteners on that cylinder this can simply be avoided by marking all Fasteners as you torque them with a paint marker it's like having your checklist
I wish all YT videos were this good cheers
Anything we work on, including industrial equipment, especially including aluminum. gets loaded and thermally cycled a few times and fasteners retensioned. Almost without exception the tension has changed. Lots of the stuff we work on has a base tension and then a specified amount of degrees of turn of the fasteners. We even did some huge presses that had hydraulic cylinders to tension the bolts holding the crank and manifolded together so all fasteners equally shared the load
This was so well done, co clear, and so informative. I fly them I dont fix them and I fly turbines but if I ever fly a Cessna or buy a plane I will definitely want my AME to know these tips. You maybe have saved lives with this video.
I think the real lesson is to pay attention to your machine, no matter what type and not just the engine, but all of it. If there's something out of the ordinary don't ignore it, have it investigated by someone knowledgeable. The first thing I said to myself when I knew he had seen an OP fluctuation and metal in the oil, was this was pilot error and he had the opportunity to save the plane right there by not flying.. His fault was knowing there's a question and not knowing the answer. The actual mechanical problem was secondary. You could say it had a mechanical problem but the pilot caused the crash.
Mike is always loaded with great & clear information. I'm very surprised tho to hear him say never use "crow's feet" adapters on a torque wrench (a 90 or 45 degree adapter to get around something in the way). Granted that he said at the outset that he has limited knowledge beyond Lyc/Cont engines, but there are charts available for this specific procedure. You multiply the normal torque value times a certain number, depending on whether the offset is 90, 45, 30 degrees.
Because these "Crow's Feet" adapters are only 'open-end' crescent wrench affairs, never sockets, it may be that if you need a high torque value then you can't do that to a nut. Putting high pressure on just 2 points of the nut will deform the whole donut AND round off the corners. My engine specs 24 ft-lbs and has a few unreachable nuts (by socket) when engine is on the plane. I used a Crow's Foot, got the correct offset values, and have had no problems in 100 hours.
This video should be mandatory for all engine mechanics. Great information! Thank you so much.
Wow! A lot of good information here!
Absolutely solid advice, very interesting indeed. Its scary to think that this isn't standard practice.
Can't say about other schools but my school tought about torque techniques, sequencing and also selecting the correct size torque wrench is very important..
Great information. Thank You !!!
Thanks, I do hobby classic cars , am also aviation enthusiast don't work on aircraft bit this is very helpful for automotive also❤
Having worked as a millwright for 30 yrs,we never used torque as a method on critical fastening on steam turbines, gas turbines and large reciprocating compressors.we use bolt stretch measured either with a specific standard or a outside micrometer.the difference between my work and small aircraft repair is cost of liability and materials, and labor.A&P's are notoriously underpaid!I have worked with a few a&p's who switched to millwrighting because of this,particurally in industrial gas turbines.Torque is too unreliable.Also fastenings will fatigue due to repeated stretching, and heat and cool cycals.The piston rod rod on a large gas compressor can cost a 100,000 dollars! Money is king!!!
Interesting, when I worked for a UK bolt manufacturer some exotic car makers (Ferrari maybe or Aston Martin) specified that the con rod bolts we supplied were tested and inspected the same as aircraft parts for Boeing, Airbus and Westland and also that the preservative used when packing them was Lanolin. Apparently their reason was that when engines were assembled the torque friction was always constant. Seems to be exactly what Mike was saying.
Very interesting video thanks a lot 👌
We had LONG discussions about this in the VW TDI diesel forums that I used to frequent when I hot-rodded VW diesels. Torque specs are only right when you use a good, CALIBRATED wrench. When the threads are lubricated (or not lubricated) according to the manufacturer's instructions. If lubed, WHICH lube? If the right lube, what temperature of lube and parts? What is he precise procedure? Clamping force varies HUGELY with some pretty subtle changes.
I just rebuilt some trailer hubs. Preload was within a pretty ridiculous range, then "backed off 1/4 to 1/2 turn." In other words I wasn't building wheels for watches. It'll be fine, and I wasn't too worried about it.
But an engine? Especially one with a split case? You'd better get it ABSOLUTELY right. I've seen the engines fail for a lot of reasons. In one case a guy replaced stock "torque to yield" bolts with race quality head studs. But missed the memo that says you have to retorque the race studs. Oops.
Clean the threads too. Absolutely clean.
So, 3200 hours and one does a top overhaul. So, how do you get to check such items like accessory gears for looseness (I've seen gears wobble about 1/6" of an inch after 2000 hours)?
Thank you for the great webinar. The only thing I question is the comment of retorquing only some of the bolts. Anytime I’ve retorqued fasteners, it loosens the others. I would think you would be better off not retorquing any of them compared to only the ones you can easily access.
Hi what a great guest. Please add a link to his CZcams channel.
This is great. Thanks.
I worked as a mechanic as a young man we would get warranty cars in with bolts that had to be replaced on Cross members and to show that they had been replaced ,they paint marked on The stud and the bolt. This showed that the bolt had been replaced and torqued properly and in the future showed that it had not moved. I actually thought this was an aviation process and I'm surprised to find it is not. I'm also surprised that they aren't safety wired but drilling the bolt & nut does lead to a weakening of the units . A commenter also mention dry torquing and reusing of fasteners .
I am curious about reusing fasteners on an aircraft and dry torquing specifications for used fasteners.
it is an interesting subject if you asked mechanics if they had worried about torque reduction when they lubricated or anti-seized a bolt possibly going into dissimilar materials what their decision was about torque reduction if any.
A "click type" torque wrench can also unknowingly fail. I occasionally check and compare mine to a dial-type and they agreed to
I cannot imagine that all of this is not common knowledge to A&P mechanics. But knowing how many automotive mechanics I have worked with that take shortcuts, I am not surprised....
A customer once asked me...How long is it going to take? I told him, that depends...Do you want it done right?
I have worked with hacks/butchers but for me there is only one way to do it and that is the right way with no comebacks. I treat customers vehicles better than my own because if it fails, it's on me only.
I've had more than one A/P try to kill me. Not all the same....
You’d be surprised how many are used to wrenching on cars in their backyards and bringing those habits to aviation. It’s almost better to train a complete noob in aviation than an auto guy using their “calibrated wrist” for torque or a Harbor Freight torque wrench on a plane and thinking a breakdown means pulling over and buying a $20 part at autozone.
Why is the resolution only 240P? Makes it difficult to read the slides.
Thank you Mike, really good, helpful information. Interesting that such a simple design engine can have such basic simple and fatal traps for the unwary.
Absolutely excellent! .... Just a we question: I clicked on the savvyaviation.com link and it didn't work?
I then googeled Savvy Aviation, up game the search page, however, when I clicked on any of the links I just get: ... "This site can't be reached" ... Are you still in business? ..... Kind Regards.
Why is 2:00 a VW crankcase? And why is the oil journals being labeled the bearing saddles?
Can you make comment on the use of copper anti-seize?
good stuff!
It would be nice to have the pie chart image at 25:25 for ‘wet torque’ as a comparison.
I had the same question as that asked at 46:00.
I understand that in applying a lubricant to the thread and mating surfaces you are reducing the thread friction and nut surface friction, allowing for more torque to be converted to pre-load, but why doesn’t over lubrication (55:15) work against you and cause the nuts to vibrate loose due to less friction holding the nut in place? Or is it a case that nut surface and thread friction will always exceed the pre-load force being exerted on the through bolt?
Lubrication on the threads will allow the nut to turn using less torque; so at the specified torque, the stud will have stretched more than if the threads had not been lubricated. The manual will say whether or not lube should be used, and what lube if any.
Then when you have completed that task, you go over to the computer, key in the required statement, that you have done the work as required by the manufactuter's manual, quote section, chapter, paragraph and figure, enter in the release numbers of any part or substance used in performing the task, key in your licence number, put in your password, and you have created a legal document that holds you responsible for those who place their lives in your hands for as long as the airplane flies, or until that particular task is redone at some future inspection. At least, that is how it works in Canada.
Still think you might like to become an A.M.E and crawl around, over, under, and inside airplanes?
So if the weight distribution of the cylindrical torque vs a washer. Won't that possible Warp the case in and cause indentation possible that then the cylindrical torque would not flatten out and this creating a next heat cycle that would cause a flux and lossiness of the pree load!?!?
Thank you 🙏🏻
At Time 19:52 This is a VW Beetle Block with the 2 Case Halves apart. The 6 Studs are the Main Case / Block Halves if you will that hold the 2 Halves together . To the Left looking at the 1 Case Half there are 4 shorter Case Half Bolts that also hold the 2 Case Halves together the 2 to the Far Left looking at this Picture actually Hold the Case Together and help hold the Engines oil Pump. When the 2 Halves are together there will be 4 Long Bolts for each Cylinder these Bolts will hold the Cylinder on to the Case when the 2 Cylinders are inserted into the Case then the Head is Inserted on to the Same Bolts as the Cylinders then there are 8 Bolts Total that hold the Head and 2 Cylinders on to one Half of the Case. The Crank, Cam, Rods and Lifters are Dropped into one Case Half Before the two Halves are Put together. At that point you Put one Piston and one Cylinder on at a Time. But Yea this is a Volkswagen Engine Case / Block very Similar to an Aircraft Engine BUT very Different.
How about the AD for ECI cylinders? I will need a top in 270 hrs. Seems the top is more dangerous than just letting it alone. Thanks FAA.
Lycoming io-360 thru bolts need complete crankcase halves separated to replace them.
Can't they groove the oil feed holes to help make sure the bearings don't come unseated?
Excellent video. I will be sharing with all the GA guys I know.
Lubricant can create pressure and give you false torque. So probably lubing up bolts but not the bolt wholes?
Do 1/2VW motors have this same 'problem' with the through bolt holding the entire motor together?
I just bought an N3 Pup and will bee the Chief Mechanic & Bottle Washer.
Your presentation was excellent. Thank you so much for posting. I just signed up for your newsletter. Again, thanks for posting.
You should start a cult based upon what you said. You mentioned things which I've never seen mechanics do, EVER. Kinda scary, but they weren't trained to do the things you mentioned.
I grew up on bug engines. The VW engine does not have head bolts that hold the engine halves together. There are large studs right at the main bearing saddles that actually hold the engine together around the crank. The head studs are threaded directly into the cylinder deck on the sides of the engine. Older bugs had occasionally had problems with the head studs pulling their threads out of the engine case. There are several fixes with varying degrees of success. The newer bugs had smaller diameter cylinder head studs that would stretch as the engine expanded thermally during operation. The "give" helped with the thread pulling problem.
Love this
great video.. one thing not touched on is torque loss with extension length.. it is substantial so should be factored...
Don't forget you can have torque gain too. If the extension is at 90 degrees to the torque wrench there is no loss or gain. I've never met a professional mechanic that didn't know this.
The discrepency between nut torque and bolt tension is a problem that no matter what you do will cause inconsistency in bolt (stud) tension. When torques are low it's less problem. Engine designers have addressed this with two modern innovations. They are torque to yield bolt design and angle torque. The torque to yield bolts have a uniform stretch that in the end gives a very consistent tension, much as a spring would do. Secondly the torque resistance is largely eliminated by developing a torque angle spec instead of torque resistance to turning the nut. Once a light, even torque is made the bolt or nut is then simply turned a number of degrees of rotation regardless of resistance. This is common in virtually all modern automobiles but unfortunately, most of the aircraft engines flying in General Aviation are of quite old design that doesn't accommodate these methods. Be sure you inspect the studs and bolt threads, make sure none of the threads are peened or dented, and taking cylinders off, moving tools around these exposed threads often damage them. I like to run a die over them by hand just to clean them up (dirt, sludge) if nothing else, but also to feel the smoothness of the threads before I put the nut on. I feel this helps get as much of a consistent tension as possible.
good discussion. only comment is that, if re-torquing, if a fastener has been "properly" installed/torqued, it should NOT move with a re-torque. you'd never overcome breakaway friction. If the fastener DOES move, then all fasteners are suspect.
Yes, if it is under-torqued a little it will probably remain under-torqued a little due to breakaway friction.
The lugs holding the wheels on your car are probably more than 800 inch pounds. The nut that holds the hub to the axle is probably four times that amount.
Just a high-intensity motor DIY guy for dirt bikes, cars, and power equipment. But, I find it rather stunning ultrasonic bolt preload measuring has not replaced the old-school torque specifications. Granted, such measurement tools exist today. But, they are quite pricey. There's nothing too rare or technical about such tools other than they fact they have yet to become prevalent.
Measuring torque is an indirect method to "guess" at bolt preload.
You answered your own question. Those tools are not prevalent, and they are unaffordable.
In the automotive engine field, measuring bolt stretch is the optimal method compared to using torque values.
USB borescope cameras of general inspection quality are under $20... Miniature video cameras are far more engineering intensive than a transducer array.
@@russellstephan6844 Engineering intensiveness is irrelevant to the cost of an item, rather, production intensiveness and demand are far more significant factors. Every smartphone has a tiny camera, but none have a precision calibrated ultrasonic transducer. There just isn't much demand for ultrasonic bolt preload measuring devices as torque wrenches are perfectly adequate for 99% of applications, and for applications requiring more precision, a micrometer will fulfill the majority of the 1%, without incurring a four-figure price tag.
It is interesting that on most modern cars i have dealt with recently, to torque a cylinder/big end/main bolt requires torquing to only 30 ft/lbs then winding the bolt/nut up another 1/2 or 3/4 of a turn.
As that got to do with all aluminium engines, perhaps the ali gives producing wrong torque setting.
Many modern car engines use TTY (torque to yield) bolts which are designed to be used once, and never to be reused under any circumstances. I wonder if that's the explanation?
@@Syclone0044 Being that this TTY method results in a more consistent tension, why does the aircraft industry not use it?
@@alansailing1387 Not the purpose of TTY fasteners. The only reason to move to "use once" fasteners is to sell expensive fasteners - they do NOT result in better tension. John Deere tractor owners using same for connecting rod bolts report an endless number of "me too" when a forum question starts with anybody else find a con bolt laying in the bottom of the oil pan? Where's the better anything in that situation? It's a real epidemic just because they greedy.
An extension on a torque wrench can be an issue if you don't keep things perpendicular and square....
You should always use the factory Overhaul Manual for the model engine you have.
I guess Im pretty off topic but do anyone know of a good place to stream new movies online ?
@Bobby Roman Flixportal :)
@Zachariah Wallace Thank you, I went there and it seems like a nice service :) I appreciate it !!
@Bobby Roman glad I could help xD
If I could afford an airplane, I could afford a top quality torque wrench.
If you're only working on your own airplane, you'll need to recalibrate your wrench every time you use it because they drift out of spec. Or get a new one. You're still trusting someone you don't know with equipment you don't know.
Milk Manson Huh? You're claiming if you do your own work, you need to treat torque wrenches as one-time-use disposable? And that if someone else does your work, it's an unknown person using unknown tools? What are you actually trying to state here?
Also, literally nobody is using brand new torque wrenches every use. They don't drift out of spec in minutes, hours, or days. Especially when treated properly and always stored reset to the minimum setting.
@@Syclone0044 If you are torquing fasteners on your own airplane every day, you're doing it wrong. How often do you think they need to be rebuilt?
And a can of the correct lubricant.
@@Milkmans_Son Aren't you also trusting a tool calibrator you don't know?
I've always been told that if a lub'ed nut is torqued, the overall torque will be MORE than if done dry. Most fasteners are torqued dry. So, it would seem reasonable if you are torquing to 100 inch pounds, the lub'ed one will "go down" with MORE preload than a dry one. I'm guessing that the engine manufacturers are taking that into consideration(?)
Believe or not this helps me alot on car engine work. But if I could get 25 years back, I would go into aircraft aviation and eventually get my PPL.
Not sure which earns more per year..........................
I fancied being an aircraft mechanic until i saw them froze working outside in all weathers. So i became a flying instructor instead.
But only earn a third or less they earn, but i am warm.
@@dks13827 If money is your main motivation, auto is where you want to be.
About the part where you showed using dummy cylinders(torque plates) if you are recommending that all the through bolts be replaced each overhaul, are you not rendering the bolts "used" by torqing them down and then having to remove the dummy to install the new cylinder? Do these bolts stretch like a "torque to yeild" bolt in modern automotive engines? These engines intrigue me as the castings and main bearing design resembles automotive engines from the 1920s.
I don't think you are far off, the technology for these engines is from the '40s and '50s. I have heard (although it could just be some loudmouth wanting attention) that it would cost too much money to certify a new modern and updated engine design. They would rather keep innefficient outdated engines going (at much higher maintenance occurance) than spend the $ on R&D to certify modern engines. Not saying the stringent certification process is not a good/necessary thing.
Wow this sounds tricky. Airplane engines seem close to the edge to ssve weight. Interesting
I like to torque back to back , rather than side by side.! Works better for balancing.!
as a non aviation mech i have to weigh in on this one. when i torque a bolt not only do i go through a patterned secondary check i mark the bolts/studs with a paint pen. it's a basic safety procedure. why is this not done as a standard practice to every aviation engine when it's worked on to ensure that these kind of failures do not happen escapes me.
then there's the dry fastener process. why dry torquing at all when reusing fasteners?
It should be. I’m an A&P and we’re taught that way. Aerospace(spacecraft) we do it that way with QA looking over our shoulders. Sometimes guys get sloppy in the field though. Especially old farts who you can’t tell anything.
Marking the bolts with torque seal does not address the problem this video is discussing. The issue isn’t fasteners coming loose, it is fasteners not tightened correctly. Two different problems.
And fasteners should be installed per the manufacturers specifications. Most torque tables are for fasteners with threads that are “clean and dry.” if you lubricate fasteners and then use a “clean and dry” torque value, you have a good likelihood of overtorquing the fastener and damaging either the fastener itself or the parts being clamped together.
Excellent info, but I agree with Mike Paul. I can't come up with anything with which I disagree, although some of the discussion could be improved.
ARP has a lube out specifically for proper torqueing and stretch.
A Wynns Lubricants salesman back in 1967 , did his little sales pitch / demonstration at the Roots Group workshop in Norwich, UK..
He got all his test gear set up and proved you can tighten a nut/stud 10% tighter with lube,,,,
On the issue at hand, I feel , if you went to the trouble to do a top end over-haul why not spend the few bucks and replace the main bearings at the same time?
Have you ever tried using never seez as a lubricant for assembly?
The internet guides from most fastener manufactures states in no uncertain terms that any fasteners drawn together using never seize need to be done at a reduced torque level of 10%, in contrast to what you heard here. You should look up several sites publishing torque values for fasteners and see if you can prove that advise wrong or not. Just my opinion, 10% overtorque isn't enough to worry about except for air cooled VW head bolts at 23 ft lbs max for the early models. They tend to pull the studs out of the block at 24.
@@leebarnes655 Sort of like how air cooled VWs blow up about 30 seconds after the low oil pressure light comes on?
After lubricating the 'through bolts',is there a possibility of hydraulic-lock thus preventing the bolt from 'going home'?
No. You're speaking of the tightening of the studs in the case... a different matter.
Mike, excellent video... Maybe you can set me at ease here. My A&P recently pulled cylinder #1 & #3 at same time on my Lycoming o-320-e2a engine due to low psi (20 psi) in #1 cylinder, and 10% reduction in #3 (65psi vs 78). After watching your video I am more aware of the concerns of replacing cylinders. With this engine should I be concerned about crank bearing moving away from the oil port after mechanic removed the two cylinders? I can contact you directly as well, but I thought this may be good for other o-320 owners - Thank you Mark
I used to work for Lycoming. I was involved in tear down and assembly. We built the engine up on a ring mount so you could turn the engine in any position to work on it. Then it would go to the test cell and be run on the same ring mount. The front main bearing halves are held in position by dowels.The other main bearings have a tang on one end that rests on the parting surface of the crankcases. They are designed to not move but if too many cold starts without preheat were done there could be an indication of this by an impression made by the tangs on the crankcase halves. Too much wear there was cause for rejection of the cases. When performing cylinder replacement in the field it is prudent to use "torque plates" if the cylinders are going to be off the case for long. These plates are 1/4" steel with a large hole for the connecting rod and smaller holes lined up with the hold down studs and through studs. The plates would be installed and the nuts put back on and torqued down to prevent the crankcases from relaxing and allowing the propagation of oil leaks. If there were any seam leaks present before removing the old cylinders, you might suspect some fretting of the cases. In that event, reinstalling cylinders and torquing them down could introduce more crush on the bearings. For peace of mind after any major maintenance of this nature, it is a good idea to invest in an oil filter at 10 or 15 hours time. Take off the old one for inspection for metal particles in the elements. Let your mechanic cut it for you so you and he/she can check for any signs of worry. Always follow the latest service instructions etc. for the latest information from Lycoming. And always get a peek at the cam and followers whenever a jug is off.
Mark Mathews we
Another reason that techs do not like to lube used torque fasteners is, the lube reduces the
friction to point, at torque load, the used threads fail and strip (which is good) . I have seen used
threads fail even after the the proper torque was achieved and then failed due to the heat expansion
load, there after. So the point here is don't reuse critical fasteners, if you do because of no alternative
and in this case at least use new nuts. maybe !.
My in-field test for bad threads is to put, sparingly, a drop of oil the nut and bolt /stud, thread it
on and wiggle the nut. If you see the oil pulsate in and out of the seam it is suspect. A new set
of threads will pulsate the oil but very slightly if any. Never reuse a galded thread
This is one of the reasons any good automotive engine service manual tells you to not reuse engine head bolts and nuts. Once a high torque, stretched fastener like this has been stretched in preload, it looses some elasticity and thus should never be used again. I know some mechanics probably reuse them but the fact that some mechanics cut corners doesn't make it right. With something as critical as an aviation engine, why would you, especially as a pilot/mechanic, ever take the chance with YOUR life and YOUR airplane just to save a few dollars on new fasteners? Get new fasteners and use the old ones on something that won't get you hurt or killed like your lawn mower, a kids swing set or maybe get a welding machine and make lawn art with them!
Angular torque has replaced torque only and solved the problem in new.s engines systems
Maybe it's just me, but it seems like avoiding certain work because you might not do it right isn't really addressing the problem.
It's insane if the manual doesn't say exactly what kind of lube and exactly how much of it goes on those threads before you torque them down.
I like how he said it during the Q@A session a lot better...
So why don't the shell bearing have the little tang that car engines have, to stop the bearing rotating and miss-aligning with the oil port.
I think its because of the little tang would stand in the way of torquing the two engine halves and the bearing shells together properly on these boxer type aero engines with the through bolts.Car engines if not (Porsche and VW air cooled) mostly have independent crankshaft bearing saddles.
@@planpitz4190 No different to torquing down the crankshaft housing on a car. There still needs a finite gap not to crush the bearing shell. Could even have a brass dowel.
Who said they don't? 34:10 shows one in a fretted condition, it's to the left of the thru bolt hole near the edge of the bearing cradle. It's an indented rectangular hole pounded into the case due to fretting. That's the tang of the opposite bearing trying to roll around but can't. Oil escaping from behind the bearing shell due to fretting allows the babbit to finally melt to the crankshaft and at that point nothing on earth will prevent that shell from rotating with the crank. Bearing crush is what holds them still, the tangs have no useful strength.
If I ever owned an airplane, this video convinced me to go with a "Factory Rebuild" provided the description of same is not contrived by a dishonest seller. It never can happen, right? My reason for watching this? I was just informed by a club member that our C-177 Cardinal blew a cylinder. The club owner/mechanic has years of experience but he is over 65 years old!!! I do not know whether he would do the work anyway.
Right way to do a Cylinder change: Obey the Lycoming Overhaul manual step by step. Then have someone else check your work (Specifically torques) after you are done.
Wrong way to do a cylinder change: Don't follow each and every step of the Lycoming Overhaul manual. Don't have someone double check your work for anything you might have missed.
Worked with a tech who enjoyed breaking off bolts. He was a powelifter he said he didn’t know his own strength . Dumbest guy . He got his head caught under a dashboard and the fire department had to get him out . He got fired after that
I wish I knew all this years ago.
Great material, just if I could stay awake.
Could have conveyed all info in less then 20-30 min.
I discovered a while ago that if you increase the playback speed to 1.5 or 1.75, you can absorb all the relevant information in a much shorter period of time.
To this day, I do not understand why "split case" construction is used... (FWIW, "Airhead" BMWs do not) I do not have an A&P, but, perhaps, my Airhead PM standards are different... seized engines at 120mph can be rather "unpleasant".
these engines were designed in the 30s (at best) and haven't really been updated since to any appreciable degree. Mainly because a. they work and b. it's too much of a hassle to get FAA certification on a new design considering the limited market of GA
Because the BMW engines are only two cylinders. Try to design a 4 cylinder without using split cases...
@@LTVoyager ...as with a VW Beetle/Porsche 6-cylinder engine?
@@johnhopkins6260 Yes, both Beetle and 911 engines use split cases just like Lycoming and Continental.
boxer and radial engines???
Yes he is talking about horizontally opposed engines mainly though, because pretty much all other engines don't work like they due with thru bolts and such.
Pausing the video to install my free Windows 10 upgrade...
A&P Mechanics are a Whole Different Breed of Mechanic than a Automotive Mechanic I am Both as an A&P I have My Book Open as a Auto Mechanic I go by my Memory the Car can Come Back if I screw up The Aircraft most Likely would not be so Lucky. My First couple of Aircraft Engines Scared me to Death but I knew that I did a Good and Correct Job. My Problem was I had Built Many VW engines and they are as i Said very Similar But Totally Different.
THE BASIC IDEA IS TO GET THE TORQUE, WHATEVER THAT AMOUNT IS, THE SAME FOR EVERY BOLT UNLESS STATED PER BOLT.
The Crush on the Main Bearings is True on the Aircraft Engine or Block Halves But Not on the VW or Volkswagen Engine.
Hey, did you know, there is a guy named Michael Bush that's much the swami as you, but he's a beekeeper and knows about as much as one can about bees. So, your evil twin is a beekeeper.
"oil filter contained an EXCESSIVE amount of metal"....FULL STOP....LOCATE AND FIX PROBLEM, full teardown justified, and IMHO warranted/required in that situation, best case, you find nothing major, more realistically, YOU FIND A LOT WRONG. That metal comes from somewhere it SHOULDN'T, PERIOD.
I might have replaced the oil and filter and done a STATIC runup to see if oil pressure was holding normally (probably not, but trying to give benefit of doubt here, maybe as one pre-teardown test), but I sure as HELL wouldn't have FLOWN the damned thing without tearing it down completely first. The downside of a tear down, cost and money. The downside of NOT tearing down and inspecting/fixing? Death maximum, likely similarly disastrous outcomes OW, like no legs any more.
And yes, by all means, when you don't know something, like is all that metal normal after replacing cylinders, do NO HOMEWORK and NO RESEARCH, don't even bother to ask a REAL aircraft mechanic or phone the factory, or ask the guy you bought the cylinders from, OR ALL of the above, just go on about your business as if nothing happened and hope for the best. Guaranteed it WON'T happen. WTH? Sorry to say it, and sorry for it happening to the guy, obviously, but Darwin at work here, folks.
I'm NOT an aircraft mechanic, so, stupid question, can you not hear a mains knock, like you can in a car engine, or "feel" something not right with MULTIPLE SPUN BEARINGS? Maybe those all occurred "simultaneously" but obviously something was open in the oil path if it wouldn't maintain pressure. I guess the exhaust noise might cover up all of it, but good grief, would this guy notice if the prop or wheels fell off. Their MUST be indications that something is HORRIBLY wrong in an engine in this shape BEYOND the fact that the oil pump can't keep up an oil "wedge" against spun "open" main bearings.
I saw in another video where a guy had constructed a plane out of DOOR SKINS, spars and all, and it "unbelievably" broke up in flight after he jumped up and down on the wing to try to see why it was leaking fuel all over the place, then flew it anyway. This doesn't strike me as that much "further out".
John Sikes In most cases it is not possible to hear rod knocking in an aircraft from the cockpit. The ambient noise level, even on the ground, is much higher than in a car.
That said, your other points are valid.
You need to fix your keyboard as the caps lock key is sticking every so often. Just as with oil pressure in an engine, ignoring a problem like this can lead to serious consequences.
@@LTVoyager LOL, best comment I've read today. I SOMETIMES reply in this ''STYLE' of tongue in cheek...VERY well DONE. Sorry, had to do it, THE caps I MEAN. :-)
Those are both unacceptable. I test run an engine and retorque when it's cool. Both probably don't have the ridiculous offset wrench end to torque.
Why do they not use synthetic oil in avaiation? I realize it wouldn't prevent what this man is talking about, but I have seen excellent results in the last 25 years in my personal autos.
Because synthetic oils don’t convey heat as much as mineral oils of what I know ..
@@loicdore39 I have never heard that. Thank you, I shall investigate it further.
synthetic oil is not compatible with avi leaded gas. It creates some bad gum that really ruins rings
Continental and Lycoming probably recommend removing the engine, disassembly and root cause analysis performed if an issue is suspected. These people having problems are either cheap, stupid, or both. Its not like you just "pull over" when your aero engines dies.
I used to see assy. errors all the time in the auto bizz. Pay attn. and leave your cell phone in your car.
Bottom line is, follow the engine overhaul manual like you are supposed to. In aerospace/aviation it is critical. Do not bring auto or home repair habits to aviation.
800 inch pounds of torque is not as much as you might imagine. 800in divided by 12in per foot is only 67 foot pounds of torque. Actually less than Ford recommends for stretch type head bolts for aluminum heads on a cast iron block and deck. Just say'n. I torque alloy cast wheels to 90 to 110 ftp with anti-seeze on both the clean studs, nuts, and wheel contact area. My question is, could a licensed a&p use aluminum based anti-seeze on these through bolts and cylinder deck bolts? I'm currently building up a c65 for use on an airboat. I know I can use anything I want on the non-aircraft application of this engine, just wondering. My guess is that the answer is no, for the aircraft application, simply because the manufacturer recommends or even specifies the thread lube. Very interesting presentation, thanks.
Remember aircraft engines are lightly built, and can be, as they have low compression, They turn slow, much slower than an auto engine so typical forces are low.. They have thin cases that have a fine machined surface to seal the two case halves together. If you look at the actual bolt tension, it's in the thousands of pounds and multiply that by the number of through bolts, and you've got a lot of stress on that thin light case. One thing you don't want is over stressed parts on an airplane where there's no side of the road to pull onto. The old air cooled VW beetle has a torque spec of 22 pounds!
If you are using anti-seize on fasteners and then using dry torque values, you are doing it wrong and will likely damage the fasteners over time from overtorquing them. Lug nuts are always specified using dry torque values.
A&P AI if you know what you are doing there is no risk at all
Amen brother, The title on the screen cap "I Hate pulling Jugs" says it all.
Where are all the A&Ps (not many posting here).
I guess its all about Mike? Hey mike I believe you forgot one "Dont pull and aircraft forward by its propeller, you might tear the engine cowling off".
Do a search for "Mike Busch" here and you'll see what I'm getting at. Here's but a couple...
1. Over at CPA. He asserted that you don't need to worry about moisture in your oil in the winter...because the air is too dry. Others had to point out to him that moisture in the oil is a byproduct of combustion, not the air.
2. But my favorite was when Mike asserted (repeatedly) that you should never stop at the SS pump upon your return home to fill up. You should instead taxi to the hangar and call the fuel truck. You'll save money by calling the fuel truck, even though the gas is higher, because every start up imposes excessive wear and tear on an engine, even one that occurs within 15 minutes of shut down when everything is still warm. He finally conceded that that he had a case of cranial rectitus on that one...don't recall if he ever did on the first example.
If he's an "aviation expert" then we're in deep sh*t.
He should rebrand himself as "savvy marketer."
I'm an A&P, & I just discovered these vids over a long holiday weekend during lockdown.
SO THESE ENGINES ARE VERY SIMILAR TO AN AIR COOLED VOLKSWAGEN ENGINE.
i have built many of both, except for the individual cylinder head on the aircraft engine vs the common cylinder head on the VW, there are many commonalities...
By similar you mean air cooled, horizontally opposed, 4 cylinder, then yes. The oil pump, magneto gearing is different. The bearings are different. The cooling changes from vertical to horizontal. The heads and rockers are different.
@@michaelvangundy226 look up the word "SIMILAR"....
@@michaelvangundy226 and yes, we all now know how intelligent you are...maybe get into the differences in the metallurgy of the crankcase and other components since you are so intelligent...
Where do you think the VW engine came from in the first place?
That was a C-85 not a VW...
Fhe VW block is at 20 minutes
Yes, the VW block comes later. It does not have the long bearing on the end of the crank to withstand the prop forces.
@@LTVoyager Generally speaking, the VW does not need the larger bearing. With the aero rebuild you should get the crank nitrided and you problems should be over. sharp turns at speed are what breaks cranks and the only VW powered planes that come to mind, that are that fast, are the KR series, but just to be safe I would always have a VW crank nitrided.... IMHO.
@@apfelsnutz I would never run a VW with a directly attached prop. They simply are not designed for such stresses. The aircraft engines have that humongous bearing on the prop end of the crank for a reason.
These maintenance management companies are predicated on the promise that they can help you avoid costly major maintenance by reading the health of your engine from temperature sensor data and oil analysis. I'm not saying those are bad tools, but keep in mind that these guys have an agenda to exploit your desire to avoid maintenance in order to get your business. Cylinder work is common enough that I'm not convinced of these perils by just a few cherry-picked anecdotes. Also the torque wrench technique is nowhere near as difficult as Mike claims -- it's elementary physics that static friction will be greater than kinetic friction so you need to achieve the desired torque after the part is in motion and not from a dead stop. I think this is a bunch of scaremongering to promote his services.
is there a reader’s digest version of this? too much rambling on