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Ending the War on Jugs
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- Опубліковано 6 кві 2024
- Historically, the rule A&Ps were taught about cylinders was simple: If the compression reading was less than 60/80, the cylinder had to come off for repair or replacement, period. This works well for mechanics, who are always happiest when they have clear-cut guidance to follow. But it was bad news for aircraft owners, who have to shell out several thousand dollars each time a jug gets yanked, and occasionally suffer catastrophic engine failure when the cylinder installation isn't done precisely right. In recent years, we've developed far more effective methods of assessing cylinder condition, catching problems early, and remediating them without the need for costly and risky cylinder removal. In this webinar, Mike Busch discusses these modern methods,techniques and practices.Savvy Aviation offers Professional Maintenance Services to owners of General Aviation aircraft, such as: SavvyMx (Professional Maintenance Management including Prebuy Services), SavvyQA (Expert Consulting), SavvyAnalysis(Engine Data Analysis) and Breakdown Assistance. Savvy also publishes a monthly newsletter with lots of interesting information for the general aviation enthusiast; subscribe to it at www.savvyaviat... text theword "Savvy" to 33777. This webinar was hosted by the Experimental Aircraft Association (EAA).
"Long, detailed and in-depth" is entirely welcome. These are complex issues with trade offs so that's the best way to approach these issues. Thanks very much for the effort!
I was thinking the same thing after reading a couple comments hinting this video is a bit too much... no way!
Big thanks to Mike B, Dave P, Ed Collin, and the team that has contributed to this day where we as piston GA airplane owners are equipped with knowledge, procedures, and tools to ensure our engines are maintained properly, minimally, and effectively. I have performed the valve lap procedure as well as the solvent ring wash method with great success. I can’t thank these people enough.
You are right on on the xylene flush. I have used it on cars, and have no doubt that it works. Have not yet done it on aircraft.
I do think that rings leak more often from sticking than wear, and how an engine is operated matters a lot.
Great video Mike! Improving safety, saving us money on unnecessary and potentially risky maintenance and sharing your knowledge - all free of charge ❤
Thank you for the awesome video!
Great content as usual! Amazes me to see people aren't retrofitting shoulder harnesses into their planes.
What's amazing is people are still driving 1957 Chevys as everyday vehicles in Cuba. And the same airplanes in America. Because Communism.
Dear Mike.
As always, it’s a pleasure to listen a MASTER CLASS A&P as you are. Experience on GA engines is becoming weak and also loads of old literature is missleading current mechanics to miss behave those engines….PLEASE MR MIKE BUSCH…..get in contact with the FAA authorities in order to update every wrong ‘ compliance-airworthy’ rule to make GA survive new era…..Big hug from ‘ Spanish stranded pilot’
I've never heard that oil comes out of the oil control rings, but rather the oil control rings scrape the excess oil off of the cylinder walls that gets there from splash from the crankshaft. I don't believe that any pressurized oil comes out of the holes rather it drains in through them. That oil then lubricates the wrist pin. This is why wrist pin failure is common in sludged up engines
That's also why these sludged up engines consume more oil because the oil control rings are not removing that excess oil from the cylinder walls and therefore it then gets burned
Wrist pins also fail from detonation.
Wrist pins are splash-lubricated by the crankshaft in most engines. Oil control rings reduce the amount of oil reaching the hot piston rings to significantly reduce coking, and oil consumption. They "control" the oil film thickness on the cylinder wall, not fully remove it.
In automotive circles, mechanics commonly employ 3 types of compression test:
1) Leak Down: Measures steady-state leakage at TDC (i.e. end of compression stroke). While it represents a critical position, running engines spend very little time at TDC.
2) Dry Compression: Measures transient leaks at starter/cranking engine speed. Tests leakage along the full compression (but not power) stroke.
3) Wet Compression: Similar to 2), with oil sprayed into the combustion chamber, for improved ring sealing (valve sealing unaffected). Excessive oil risks hydraulic lock. I suspect that oil sealing is most effective with vertically oriented cylinders, and least effective with horizontal cylinders.
Ideally, such tests are conducted with a hot engine, as a cold engine compression test would only represent cold-starting conditions. I imagine that (even large) air-cooled aluminum engines cool off rather quickly, compared to liquid-cooled engines. It seems that flying for "at least 45 minutes" does little good to stabilize its temperature, when it takes several minutes to descend, land, taxi, and remove spark plugs.
This is such an eye opening video! Amazing content! I can't wait to see how this changes engine maintenance. It seems to me like a lot of engines are being prematurely overhauled when it's just a valve that needs lapping or a gunked up cylinder.
With the costs of GA killing our industry, any technique that prevents a widely practiced unnecessary (If not dangerous) process from being done is priority to be wholly approved and dispersed.
Interesting statement
Mike you would be a great couples counselor... Maintaining the suck squeeze bang blow part is a very good way to keep things together and flying 😂...
Aviation Maintenance Technician of the year sounds like a ridiculous award - until you think that you probably don't want a plane (or part of one) to fall on your head.
If it needs it, it needs it. Skill of the mechanic is the key to success or failure. You can't regulate enough to change that
I find it interesting that you can actually hear the solvent going through the ring holes.
😁 Thank you very much! Excellent material based on factual observations.
Not just about flying after engine work, but also flying post paint work as well. After painting, all the control surfaces have to be reinstalled, the engine was sitting for a long period time, and possibly get contaminated with all the chemical washdown. Yet I often saw owners of newly painted airplane took off and flew home or somewhere else without doing post paint inspection flight. I saw owners rushing to leave the airport for long overnight trip in their newly painted airplanes. Or sometimes, they hurried to takeoff to escape the incoming bad weather.
Not to mention, they require re-balancing all control surfaces within specification, as fresh paint behind the hinge-line adds weight. Causing flutter margins to be substantially reduced.
1.25-1.5 speed is the best modification for this channel to be bearable.
Mike is soooooooo sloooooooow.
I like the delivery just fine!
Aircraft go fast enough, pilots and maintainers need to slow down a little bit more than the average corporate nut case.
I always listen to Mike at 1.5, that makes it normal speaking speed for me 😅 Very grateful for this stuff Mike!
If you don't like free content, then just don't watch it.
Agreed! I always increase the speed on these videos.
Another great one. You are awesome!!
Thanks Mike. I've watched most/all your videos over the years. Q. When you take your airplane to a shop and you are told it needs cylinder work, how can you be sure that your particlar mechanic/shop is absolutely not going to create a time bomb for you with some of these catastrophic failures.
Same way you know your pilot won’t fly you into the ground. Stark but true.
Trust and word of mouth.
Video of work should be compulsory as this would satisfy bouth party's
@@cedhome7945 I’d like a copy of a pilots resume before hopping on any plane. Plus video wouldn’t show a whole lot, and the owner would be paying for the extra time, and I’m not feeding lawyers any more fuel. Not at to hide anything.
Own assisted annual inspection is the only way to go. If you find a great mechanic, he might be open to these newish techniques.
The bore scope can help get the replacement parts faster as what parts are damaged can be assessed and parts ordered before the actual tear down takes place.
What is the usual mistake with removal or re-installation that leads to subsequent these disastrous cylinder head failures?
1:23:25
Exactly what is causing the failure after the repair that should be the main concern
@@kennethbawol8800 it sound like any of a dozen actions that are not performed 100% correctly. The whole reinstallation is the single point of failure.
Piston rings alignment, compression, strain, cracking. Loosening and Re-torquing cylinders. Not to mention removing valve rockers and pushrods. Too many critical components are being molested and re-installed after proving to have been properly instaled in the first place, by surviving ~1,000 hours in service already. Why try to fix what ain't broken?
If you have to send another A&P to tighten some screws, have him also bring some marbles to replace the ones the other guy lost.
How much is a typical cost to replace one cylinder vs all six cylinders?
FAA records show Horizontally opposed air cooled aero engines have a mean time between in flight failures of around 3,600 hours. The vast majority of those happen within the first 2, 20, and 200 hours from new or overhaul. Or after 2,400hrs in service. The ideal range to have an engine is the 2,000 hours of reliable service between 200-2200 hours time in service/since overhaul.
We are talking more than half of all catastrophic failures happen between 0-200 hours vs 200-2,200 hours. You have a 10x greater chance of engine failure by messing around with an engine.
There must be a legal reason he just will not say WHY engines are failing after a major repair
It's simple. They partially disassemble a perfectly functioning engine and re-assemble it with formerly broken in, used parts, that were happy working together prior to being removed and left sitting around the shop. Re-installed and re-torqued not in perfect alignment to where they were previously broken in at. And then all of the human errors that can be introduced at this point.
The best thing to do is ditch horizontally opposed, air cooled engines that haven't had any improvements in over 60 years. Not even Nikasil cylinder bores, or sodium filled exhaust valve stems.
Consider soaking the rings in case of serious sludge with a higher acetone. Over night or a few days... Just a thought 🤔
THE ONLY PROBLEM WITH YOUR RING FLUSH IS CLEANING THE TRASH OUT OF THE CRANKCASE SO IT WONT END UP IN THE BEARINGS LEAVING YOURSELF WIDE OPEN FOR A LOT OF LIABILITY THE VALVE LAPPING AOK
Years ago when i worked at a FBO as a summer job whilst studying for my Mechanical Engineering Degree. I learnt a really related lesson. A Cessna 421 came to us with a misfire on one engine. A compression check showed very poor compression on one cylinder. It turned out to be 2 bad plug wires on the offening cylinder. New plug wires and the cylinder recovered.
Please explain. Are you saying that the cylinder was not operating at optimal pressure and temperature, therefore changing the ring seal during a pressure leak down test?
I would guess so as the cylinder (and the engine performance) recovered. It was only the persistence of an experienced A&P and the owner that found the real fault and stopped the pot (UK speak) being pulled.
Sounds like a ring issue from running many hours without firing on that cylinder.
Maybe but it did make the last 150hrs remaining to the TBO I believe. I don't think it had been like it too long as the pilot had returned due to rough running only 5 or 10 mins into the flight. I would be more worried about any damage from detonation. Not the most forgiving engine, but they did sound great.
TO CLEAN A PISTON ARM YOU WOULD REMOVE THE SPARK PLUG, MOVE TO TDC, POUR IN THE MIXTURE, THEN MOVE THE ARM DOWN, THEN BACK UP TO REPEAT THE PROCEDURE?
To call the 1947 bonanza manual "current" when Beechcraft themselves have changed parts since 1947....
Negates the meaning of the word "current". It renders that word meaningless. Why use it at all?
I am not disagreeing with your statement on that, however. I have read that interpretation myself.
In disbelief.
I think phone books were printed in 1947, also.
Are they current? Currently, I mean..are we speaking English, here?
The Feds are not.
In addition to the ridiculous faa interpretation of "current", consider that resting on that crutch may be of no use when it really counts.
THAT moment is not when the Feds decide you didn't technically violate an FAR- no. It is when the lawyer representing the families of the dead people in the burnt Bonanza are asking you in court "Why did you use 76 year old service information, when the MANUFACTURER of this aircraft has themselves provided MORE current data?"
At that moment, the FAA is probably the least of your worries.
@@firstielasty1162it’s aircraft MX, we are dammed if we do or damned if we don’t.
And at that moment, in court, with the lawyer- the FAA won't lift a finger to help you!
Here’s the thing, I’ve heard this guy bloviate for years poo-pooing mechanics for engine failures. He tends to paint all mech anics with a a broad brush and it pisses me off. if you go look at the NTS reports on the fatals, other variables existed. He’s not a big fan he says of compression tests. So he is saying because I got an award in 2008 I know more than the manufacturers do. Here’s what Lycoming says:
Typical Differential Compression Measuring Device
1.Operate the engine until normal cylinder head and oil temperatures are attained; then shut down the engine making sure that magneto switches and fuel supply valves are shut off. Proceed with the test as soon as pos- sible after shut down.
2. Conduct the test in accordance with the test equipment manufacturer's recommendations.
3. Interpretation of the results of the test is highly dependent on the skill and judicious opinion of the tester; however, the following observations cover the principle factors to be noted:
a. Pressure readings for all cylinders should be nearly equal; a difference of 5 psi is satisfactory; a difference of 10 to 15 psi indicates an investigation should be made.
NOTE
Unless the pressure difference exceeds 15 psi the investigation should not necessarily mean re- moval of the cylinder; often a valve will reseat itself and result in acceptable compression during a later check which should be made within the next 10 hours of operation.
b. If the pressure reading for all cylinders is equal and above 70 psi; the engine is satisfactory; less then 65 psi indicates wear has occurred and subsequent compression checks should be made at 100 hour intervals to determine rate and amount of wear. If the pressure reading is below 60 psi or if the wear rate increases rapidly, as indicated by appreciable decrease in cylinder pressure, removal and overhaul of the cylinders should be considered.
c. Low pressure in a single cylinder is indicative of air passing by the piston or by the valve.
d. Air discharged from the breather or oil filler tube indicates leakage in the area of the piston and rings. e. Air discharged through the intake system indicates leakage at the intake valve.
f. Air discharged from the exhaust system indicates leakage at the exhaust valve.
This is from the same 1191A bulletin.
I do agree with borescope inspection, been doing it for 20 years if not longer.
Another thing he fails to mention is liability but worse yet absorbing liability with an owner who wants to only do the bare minimum or even less. Ignorance or just plain not giving an airplane the same level of care they do their Mercedes just baffles me. For those of you who care, EVERY modern manufacturer (post 1960’s) has an inspection guide that goes into further depth than Part D does. If a mechanic still does an inspection I/A/W Part D, rest assured he missed ALOT of things. Back to the issue of liability, lapping valves in place is more accurately performed in a bench by shop who does that function every day AND as an extra added bonus. A repair station who will issue an 8130 for the repair. I will make this argument, In my opinion if a cylinder is bad enough to require lapping, that is plenty enough reason to pull the cylinder off because as y’all have seen in some of this pictures seats are worn, valves do not sit square in the seat which is a sign of worn valve guide which will most likely have have oil seepage which will like foul plugs. He also doesn’t mention engine time, I could go in and in poking holes but you get the message.
A field landing would be a lot smoother when parallel to the rows.
If the scope inspection and owners' assessment of recent performance says nothing's wrong, you should do a hot test. Borescope inspection I would think would assess the walls. The valves and seal probably should be assessed, but what does good and bad look like with the borescope? I would doubt you could see the rings, if you could that would have to be explained. The thing about noninvasive repairs is you may lose a cylinder if you did not do a good job, but you have little chance the whole engine will go out because of something you did.
There is a topic on minute 93…screw’s tighten…..there should always been a simple directive on how much pressure every screw has to be tightened….CURRENT ROAD CARS HAVE IT…
A BOROSCOPE INSPECTION IS STATED AS REQUIRED IN MOST MANUFACTURERS MANUALS AND THE BOROSCOPE COULD CLEAR THE ENGINE IF IT IS A HOT ENGINE?
THE MIXTURE PROCDURE FOR CLEANING THE PISTON ARE IS MORE BETTER THEN PULLING THE JUGS?
THE BOROSCOPE INSPECTION COULD REVEAL A WORN IN AIRPLANE THAT WOULD EVENTUALLY BE GOOD OVER TIME?
SO, IN THE AC YOU SHOULD TRY THE TEST ON THE STAKING VALVE AGAIN? BUT IT SAYS NO REBUILD?
THE COMPRESSION TEST IS USUALLY DONE ON A COLD ENGINE AND IS UNRELIABLE BECAUSE OF THE ENGINE FLEXION?
SO, THE INTERNAL ENGINES TO INSPECT EVERY 100 HOURS OF ENGINE ABD NACELLE GROUP FOR COMPRESSION AND FOR SUMP PUMP DRAINS AND CYLINDER HEAD FOR METAL SHAVINGS, AND IF THERE IS LOW COMPRESSION CHECK TOLORENCES?
SO, IS THE 60/80 RULE IN THE FAR, NO IT IS ON MENTIONED IN 14 CFR TO INSPECT COMPRESSION?
SO, THE REBUILD COMES FROM AC 43-13-1B? IT DESCRIBES COMPRESSION TEST AND READING? IF THAT FAILS THEN THE CYLINDER MUST BE REMOVED AND INSPECTED? THE TEST MUST BE DONE ON A HOT ENGINE AND MOST PEOPLE DON'T DO THIS?
IF THE READING OF A COMPRESSION CHECK IS 60/80 IS STAYS ON THE ENGINE?
SEE, THE MANUAL MENTIONS REPLACE RINGS AND CLEAN THE CYLINDER COMPRESSION ARM?
THERE IS USUALLY A CYLINDER SEPERATION IN FLIGHT CRASH INSPECTIONS?
Dumb question - what are the numbers "60/80" signifying?
I'm not an aviation mechanic, but I've done plenty of automotive compression tests, and we just use one PSI number. If it's over 90 for a "low compression" engine or over 120 for more modern gas engines, and all cylinders are within 10% of each other, it's fine. Then we have separate leak down tests to check valves, valve seals, and piston rings.
It’s holding 60 PSI with an 80 input pressure. In other words leaking 20PSI.
@@TheReadBaron91 Thanks!
THE CYLINDER IS THE TOP OF THE HEAD AND EVEN PISTON?
SO, MANY MANUFACTURERS SAY REMOVAL AND OVERHAUL SHOULD BE CONSIDERED?
The accidents at start of video drive home how wearing helmets, or having them available, is important in GA. We don't have airbags... I go with an in-ear headset and a bicycle helmet for takeoff and landing. Convenient as I usually have a bike with me. But still, the vineyard person would likely be in better shape had they been equipped.
Bike helmets are inadequate protection for bicyclists. Let alone any other use.
Ski/snowboard or skate/vert helmets would be the bare minimum for those activities. Motorcycle/scooter helmets would be closer to Aviation use.
SO, WHAT IS THE CYLINDER?
THE CYLINDER OF THE ENGINE HAS BEEN PULLED OFF MORE THAN HAS TO BE?
SO, MANY INVASIVE PROCEDURE CAN BE DONE LIKE LAPPING THE EXHAUST VALVES, REPLACING COMPRESSION RINGS?
I’m very curious if this applies to auto cylinder compression tests as well ? I find it very interesting the bore scope is more reliable than the gauges.
Not really more reliable, just tells you different stuff or the why.
THE COMPRESSION TEST WERE UNRELIABLE?
I came here expecting some sort of state action against hooters.... and leave baffled by technical talk.
I'm def team jugs over team stabilator
AND THE AC SAYS THE MANUFACTURERS GUIDANCE TAKES PRESCIDENSE?
OTHER MANUFACTURERS SAY 40/80 ALSO?
IN AIR CRASH LITIGATION THERE WERE A LOT OF CRASHES INVOLVED IS CYLINDER FAILURE?
1,000s
BUT EVERY TIME A CYLINDER CAME OFF IT WAS A $3000 EVENT?
SEE, ABOUT LAPPING THE VALVE THE PERSON USING IT MUST DERTERMINE CLEAR AND REASONABLE BASIS BECAUSE YOU STILL HAVE THE SAME VALVES AND THE MANUAL SAYS LAPPING IS OKAY?
APPENDIX D SAYS YOU CAN USE A BOROSCOPE TO CHECK THE CYLINDER AND NOT TO REMOVE IT? BUT APPENDIX D SAYS YOU CAN?
Could you please respond to a reoccurring statement that you made in the video. “Field Cylinder Replacement “ was the curious word sequence that got my ears spinning, could you please clarify “field “. Dirt field as in where you would maintain a farm machine, or FBO, manned by licensed, trained, experienced A&P people?
In the field means not at the factory.
Torque is the word
THERE ARE SAFTEY RISKS TO NOT REMOVING A CYLINDER?
ALSO, ANOTHER INVASIVE PROCEDURE IS THE ROTATOR SPRING CAP REPLACEMENT?
THE ADMINISTRATORS CLAUSE DESCRIBES THIS ACCEPTABLE TO THE ADMINISTRATOR?
SO, WHEN CHECKING THE PRESSURE CHECK REMEMBER TO BOROSCOPE THE ENGINE TOO?
A BOROSCOPE HAS BECOME VASTLY LESS EXPENSIVE AROUND $300.
$30 on Amazon
LAPPING MAKES THE VALVE CONTACT AREA IS TREATED WITH A CHEMICAL TO MAKE IT SMOOTH AND SHINE AGAIN?
Lapping compound is like Jewelers polish.
It has fine particle abrasives in a paste.
You lap the valve my spinning it carefully and this abrades the surface of the valve and valve seat to fit close tolerance of 0.0001" or better.
IT DOESN'T REQUIRE AN A&P TO DO A BOROSCOPE INSPECTION AND IS PREVENTATIVE MAINTENANCE?
Pilots can usually change spark plugs, filters, and oil as owner maintenance. You can purchase borescopes that work with android phone apps for $25. If you can remove the plugs, then you can scope the bore.
You use a couple of repairs as an example of cylinder changes. Do you realize how many cylinders have been changed over the years? You totally sensationalize these accidents,. Do you work for FOX news?
Not cylinder changes. This is regarding invasive inspection procedures such as partially disassembling a perfectly good engine to check wear, when there are zero signs of wear by all other tests.
If you haven’t realized, scaring owners is how he makes money. Don’t get me wrong there ARE some bad mechanics out there, just as there ARE bad pilots.
BUT THE AC IS PRACTICALLY THE LAST WORD ON THE REBUILD BECAUSE IT SAYS IT DOES NOT SET A GUIDELINE?
I don't know why this guy is so uptight about cylinders all you have to do is follow the procedure
Mike's message is pretty clear in literally every video. Don't touch things that don't *need* to be touched (as long as you're properly maintaining and caring for your aircraft). Specifically, if you can use a modern tool (borescope) to determine the ACTUAL condition of an engine, the only time you'd need to remove the jugs is when you KNOW its condition warrants that level of work.
Some mechanics will never get it wrong but why take the risk when there is no upside vs the less invasive and more accurate process?
@@cbbbbbbbbbbbb I'm just saying that when it is time to change a jug he makes it sound like it's the most dangerous thing in the world. And it can be if you don't follow the procedure
And if every procedure in any dicipline was followed properly we would never have accidents. Same for people following the speed limit and not staring at their phones while driving. The problem is that removing a cylinder multiplies the opportunities for mistakes when there are a few things that can be done first to fix the problem and reduce the opportunities for mistakes.
@@jimstanley_49 Wet torque with new hardware and clean mating surfaces.it's not that difficult. Whith multiple cylinders use torque plates and do not move the prop. Seriously it's not that difficult
@@derheeheehee6941 there's a saying, you can't make something idiot-proof. The world will just create bigger idiots. Same rules apply. Doesn't matter how simple the job, if you can avoid it entirely with the same result, that will be better than giving someone the chance to screw it up.
But in this case, you have a better diagnostic result. In the end, if the jugs have to come off, they'll need to be put back on properly, but there's no point wasting time and money when you can do a better job that is safer for less.
SEE, IN THE AC IT SAYS ACCEPTABLE TO THE ADMINISTRATOR SO WHAT IT DOESN'T MEAN IS APPROVED? N8900.444 DESCRIBES THIS? SO, THE MANUAL SAYS REPLACE AND LAPPING THE VALVES?