Inside the Crankcase
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- เผยแพร่เมื่อ 16 ก.ย. 2018
- The crankcase of your aircraft engine contains the crankshaft, camshaft, connecting rods, bearings, gears, and other components that are collectively known as the "bottom end". Mike Busch takes you for a guided picture tour of these components. SavvyAviation 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 Breakdown Assistance. For more information, visit us at savvyaviation.com. This webinar was hosted by the Experimental Aircraft Association (EAA).
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I’m only 3 years into my aviation mechanics career. I’m going to sign up for these webinars. Really good stuff ! I’m trying to get my A&P and I’m just about 30 months so I’m looking forward to joining the ranks very soon. My dad was an A&P at MATTITUCK airbae overhaul shop for 25 years until they shut down so it’s in my blood . I tried to do other things for years but I guess you just can’t fight your biology lol.
Thanks again this was great to watch !
Congratulations
Awesome video, thanks for the job of making this video available for everyone who want to learn, very helpfull in my goal of obtaining the A&P! Saludos from Chile!
Thank you for doing this, Mike.
I'm not an A&P but I find this video interesting and informative because I was always wondering how these air cooled engines are built. Sounds similar to a Subaru or VW engines are built. Again thanks for these videos. The pre- lubing is why you do a blade count before turning on the magneto on aircraft with a radial engine (DC3, DC4, Lockheed Constellation, etc).
This was excellent. Alway more to learn
Very , very insteresting and helpful video ! Thanks Mike !
You're saying that we have to hold some of the A&P's hand?
Having said that thanks for your videos and you're clear explanations for us experimental guys
Thank you for all of your videos. I’m really enjoying learning from your channel.
Mike, your knowledge is truly encyclopedic. I've been a pilot for 58 years, and you're teaching this old dog new things. Thank you for sharing.
Great thank you
Crankshaft free play also known as end play or the a and b dimension in the overhaul manual, is not determined by bearing position. It can only be adjusted by grinding the crankshaft per the overhaul manual.
The tremendous required torque on the through bolts, and the tendency for bearings to displace suggests something to me: it seems the case has a tendency to warp or distort. With the through bolts torqued down that stress doesn’t go away, it just shifts around. “Nobody has published a study on the fatigue life on crankcases” (paraphrasing maybe). I suspect that crankcases crack under these stresses. Distortion could also put strain on the crank, contorting with each revolution. Possibly also putting strain or imbalances on con rods. Your thoughts?
I was a little surprised by the 26-tooth idler gear illustrated. Why not 27 teeth? Wouldn’t change the 2:1 crank:cam ratio but it would distribute wear. And, are those gears helical?
Thanks!
Very informative!
Crankshafts are dynamically balanced, just FYI.
On the question of aluminum crankcase corrosion: Aluminum immediately corrodes upon contact with oxygen and creates a fine layer of aluminum oxide, that then serves as a protective surface layer to assist with deterring continued corrosion. When you pick up aluminum tubing and work with it for a while, your hands will turn black. That is from the aluminum oxide layer. So technically, yes...aluminum corrodes, but if that surface layer of oxide is not disturbed by wear or damage, there is no further corrosion.
Good
I enjoy your presentations immensely. While the engines look sort of primitive as compared to today's ICEs, it's the simplicity I like most. I have always wondered why the engines were not equipped with a "pre oiling pump" for the lack of a better term. This would eliminate the dry metal-on-metal contact just after startup. A simply 12v pump would prime it quite nicely. Will adding this extra weight and complexity make this prohibitive? As far as I know, this may have been done or is currently in practice. Is there an STC for something like this? Thanks,
Cheers from Louisiana!!
How do you visually inspect via perhaps a bore scope a Lycoming 0320 cam lifters?
The plain bearings Are keyec to the case so they will not move, this assumes the bearing has not spun
How much torque must be placed on the cylinder bolts of an IO-360-C1C6?
You mentioned the case mating surfaces may be resurfaced by taking a little metal off the surface. Wouldn't this decrease the distance of the cylinder to crankshaft connecting rod journal and thus force the piston further up to the top of the cylinder? Is there enough clearance between the piston and top of the cylinder at TDC to allow for the case resurface?
Refacing crankcase halves typically removes .0005 - .001" from each parting surface. Deck height (what you're referring to) is inspected upon engine reassembly.
Aren't the so-called thru bolts actually just long studs, since they are threaded on both ends, and not tightened to a specific torque value into the engine case, with the torque strain being applied by the nut on the other end on top of the cylinder base?
Tom Clark Yep...but they call them thru bolts.
Just happen to be reading the tsio-520-ae while listening. 690-710 in lbs on the thru bolts. 58 ft lbs doesn't scare me much coming from the automotive world. I've seen other mechanics put that much torque on some not very large fasteners and it's lower than any cylinder head spec I've ever used.
Thanks teacher very good please subtitulada spsnish
Is STP oil treatment allowed for aircraft engines? It would definitely put an end to the problem of cam and lifter failure due to loss of lubrication from sitting for months.
Andrew Armstrong not sure about STP, but I know of at least 2 oil additives used in aircraft engines. CamGuard is one of them.
Mike talks about that in his break in video (saying not to use it during break in).
No place for ZDDP in aircraft engine oils. It generates too much Ash and Will make it prone to preignition.
STP will increase the viscosity of our already very thick aviation oils. Higher viscosity leads to a longer period of time before critical bearing surfaces are lubricated, but more importantly, increased oil temperatures.
Cam guard works very well at preserving the lubrication film between the cam/lifter interface and propagating a chemical bond to ferrous metals.
Rule of thumb: If it's approved for cars, it AIN'T approved for planes.
To prevent a spun bearing, why don't the bearings have some kind of feature that positively locates them?
It's a misnomer, spun bearing.
The cause is not the effect. If the crank welds itself to the bearing due to lack of oil, the bearing will fuse itself to the crank.
The bearings are precision fit and are unable to move around much when properly installed. Probably only a thou or less.
Is the purpose of the torque plates to not mar the surface of the case? Or to distribute the force across the area? I’ve only changed one cylinder at a time, only tightened the thru bolt back up without a plate.
Caleb P Torque plates are used on through bolts to maintain main bearing crush while a cylinder is removed. It is possible for a main bearing to spin if the bearing crush isn’t maintained.
How is proper crush determined? Do you use red or green crush strips like in a car engine?
Andrew Holland torquing the plate down to keep the case from separating. Take one cylinder off, install torque plate, next cylinder and so on
How come bearings don’t “spin” on initial build up of the engine? Cranks must be turned to install cylinders. Why is this malady only related to top overhauls?
Assembly lube is placed in the bearings during assembly, and they probably use torque plates during initial assembly.
Muy bueno , pero tendria de ter una traducción en español
Claro! Y ya que estamos también al indio, francés, italiano y alemán.
De acuerdo
Why would manufacturers continue to make bearing shells that can freely rotate in the saddles? Any small surface feature, such as a single rib and a matching groove in the saddle would do away with the spun bearing phenomenon for good.
Why aren't pre-lube & post lube electric oil pumps installed on piston aircraft engines.
That way all engine starts would be under full oil pressure.
Also post shut down would cool hot engine parts (I.E. turbochargers).
On more sophisticated and larger radial engines the pre/post-oiling and starting/shutdown procedures are quite different. Usually, pre-oiling is accomplished by an electric pump. Then, the starter is engaged with the magnetos on, but with no fuel in the engine. Then, after oil pressure comes up again, the electric fuel pump is engaged and the engine starts. Warmup is also very important for any pushrod engine. The warming oil is circulated at low RPMs. By doing so, the critical engine parts actually expand. If you have ever seen a cold radial engine that is not leaking oil, it's because it's oil level is too low. Almost all pushrod engines (especially overhead valve types) cannot make their rated horsepower for takeoff until the pushrods grow long enough to fully open the valves. Then, upon shutdown, because all radial engines have a dry oil sump, the leftover oil in the sump is removed via an electric pump back to the reservoir to help prevent hydraulic lock should that oil drain back into a lower cylinder combustion chamber.
You can simulate the pre-oiling by cranking an opposed cylinder engine with the starter with the ignition off or the fuel restricted (either by selecting no fuel at the fuel selector or idle fuel cutoff with the mixture control) until oil pressure is indicated. Then, simply turn on the ignition or the fuel to the engine. Because opposed cylinder engines have a wet sump, there is no need to de-oil the engine. Of course, to help eliminate thermal shock, the engine should be allowed to cool whilst running at idle before shutdown.
As usual, there will be a test on Friday.
Harmonic Dampers, not Dampeners.
Semantics
@@TheJustinJEngineering terminology. Dampeners make things wet.
I thought it was a SILVER thread used to seal the cases...
applesnutz ~ It is definitely pure silk from the silk cocoon of the silk moth.
honda bond is the shit ....super sticky leak proof seal