Fortunate Catch
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- čas přidán 9. 10. 2023
- A maintenance-aware owner is the last line of defense against maintenance errors. In this webinar, Mike Busch A&P/IA relates the story of one Bonanza owner whose shop replaced two cylinders because of burned exhaust valves. Then, just as the mechanic was buttoning up the airplane in preparation for the break-in flight, this maintenance-involved owner looked closely at the newly installed cylinders, spotted something that concerned him, raised his concerns with the shop, whereupon the A&P who installed the cylinders admitted that he'd made a critical mistake that almost certainly would have resulted in a catastrophic engine failure had the vigilant owner not saved the day. Mike also talks about the crash involving another Bonanza that suffered a catastrophic in-flight engine failure years earlier caused by precisely the same error and was the subject of landmark litigation. Savvy Aviation offers Professional Maintenance Services to owners of General Aviation aircraft, such as: SavvyMx (Professional Maintenance Management), SavvyQA (Expert Consulting), SavvyPrebuy, 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.savvyaviation.com or text the word "Savvy" to 33777. This webinar was hosted by the Experimental Aircraft Association (EAA).
- Auta a dopravní prostředky
This reminds me of one of your previous videos, Mike, where you showed how technique-sensitive cylinder installation is. Here is another reason to seek out an experienced engine shop. Thanks again for being so generous with your knowledge!
This is a great topic because it gives you something to think about in connections of all aspects of an engine.
The cylinders coming back from a rebuilt shop should be mandated to install a wired on warning tag NOT to use any sealant on the cylinder base during reinstallation.
and they would still ignore that most likely!
The aircraft or engine maintenance manual specifies what is approved for use. The mechanic must follow those procedures. Making “improvements” or deviating from written procedure is not a good idea.
@@raoulcruz4404 and yet, they still do it! "I've been doing it this way longer than you have been alive sonny!"
O-rings seal by their design. Anyone who would add RTV to an O-ring would give me pause . I say this politely, but it was not my first inclination.
While I can see how someone would think “if one method of sealing is good, 2 would be better”, it’s flawed thinking. Rubber o-rings should have a little lube on them. Metallic o-ring or “fire rings” should absolutely be bare.
/@@ghigrips1978 And that is how it is done! Well said.
Had a broken stud with a missing nut on my 1977 M20J Mooney. Mechanic found it during annual. Happened between April and August this year.
As an A&P, the worst call from the FAA about an aircraft crash where you name is in the log book
.
Very good advice.
I had a cylinder separate from the case on an A-65 Continental years ago leading to a forced landing. Fortunately I was near a friend’s grass field and the outcome was successful. Cost me a major overhaul.
Supposedly the engine had 350 hours SMOH. I now wonder if my issue was caused by something similar.
I have a digital copy of the Lycoming overhaul manual for an O-360. When installing a cylinder on Lycomings, while it does not have a warning like the Continental manual, it mentions nothing about anything being put on the base seal. Not even any oil.
How old is your manual revision?
Thanks Greg. I have a Mooney M20C w O-320 and troubleshooting rough (at times) engine. Annual due in 2 weeks.
I can just see the mechanic justifying it by saying “but I’ve always done that”. 🤦🏻♂️
Pilots say that too 🤦♂️
@@TheReadBaron91 I’m sure they do
It's usually the old heads that always do the sketchy stuff.
My guess is this was a trainee-jr mech without adequate supervision. I only say this because there was such an over-use of RTV for any type of application. In this case it was a good thing as it alerted to procedures that were not followed.
Fascinating story. How many engine cylinders with RTV applied would you guess are out there waiting to fail sooner or later? Frightening to say the least. Are there pilots who are now experiencing sleepless nights wondering if their cylinders have been sealed with RTV? I bet there are.
The rtv "extrudes" in both directions. The "worms" of it inside the crankcase tend to fall off and end up in the oil suction screen, where it isn't welcome. I have seen it in airplane, car, and motorcycle engines.
The pictures of both the rtv and the TCM gasket maker on the cylinder mount surfaces looked like more had been applied than "just a little on the o-ring". I guess it depends on your definition of "a little".
And yes, none should have been used on either the o-ring or the flange.
I think the TCM stuff is just repackaged loctite 515, but loctite has more products than you think, maybe it is something else.
If I wasn’t in my 60’s, I’d go back to school to get A&P certified. It looks like a cool position as I’m naturally blessed with mechanical inclination and most of all, common sense; Which is lacking in today’s society.
Would the mechanic that gooped up Coreys engine have done the same thing when working on other airplanes?
Looking at the image @ 12:44, I see a case with lots of carbonized oil. That indicates a long term oil leak, that happens to coincide with the studs with the backed off nuts. Why was this not discovered during it's annual? Another question is what kind of studs are these? Are they single use and/or stretched? I also question whether they were tightened in the proper sequence or torque value.
Wow, that’s an amazing story. Typically gasket maker is for valve covers or something like that, not compression sensitivity or pressure sensitive surfaces. Especially on close tolerance machined surfaces.
'Brylcreme, a little dab'll do ya, use more only if you dare, but watch out the Gals'll all persue ya... they love to get their fingers in your hair..."
As an auto mechanic myself, how can a certified A&P maintenance technician make a mistake this catastrophic ? (Not the engine but his decision)
The 'through bolt nut" appears to not have any threads remaining. Shouldn't there be 2-3 threads remaining?
RTV Sealant on the crankcase halves will cause a loss of bearing crush and the engine can spin a bearing.
Not cross torquing cylinders is the cause of crankcase halves leaking. Silk thread halves will not leak with proper maintenance practices.
This is because so many mechs and even IAs don't read the documentation, they "think" they know, and even I fall victim to it occasionally, and have to kick myself back into reality. Sign of the times, everyone is lazy to some degree, some more than others, and the consequences vary from none at all to extreme!!! I get tired of hearing so much opinion stated as fact or used to justify a practice, that I just have to work alone, so I can do it by the book. I am grateful I have been able to find a good IA to work under that believes in the importance of the available documents.
You must have approval to do something to your aircraft. Some owners put Marvel Mystery oil in their engines. This is improper maintenance. Is MM used in automotive engines? Yes. But there is no approval for aircraft. Same with RTV or even approved sealants. There must be approval to use it in that specific application.
Do you recommend new nuts when installing cylinders?
Of course you use new freshly cad plated nuts
Continental Motors didn’t invent red RTV gasket maker. How could Continental claim that ? Or was their version a special chemical compound for aviation ?
I run my O-290 on mogas and when I borescope the cylinders the exhaust valve is always a solid off white with some sort of ash like combustion byproduct coating. Not sure what it is. Some ppl report the same thing on cars sometimes.
White residue usually means the presence of ethanol. At least, it has no carbon on it.
Hmmm. The fuel I'm using is from a mogas supplier that is supposed to be providing alcohol free premium for aircraft use. But I'm going to test it now. Thanks@@tomasnokechtesledger1786
If your mogas STC doesn’t approve ethanol gas, then you must use non-ethanol. Generally speaking, ethanol is bad for GA aircraft.
It's a homebuilt. Not applicable. Ethanol can be rendered a non-problem by replacing the alcohol sensitive parts, fuel exposed rubber mostly. My fuel supply source is used by other a/c with the STC and the source is supposed to be eth free.@@raoulcruz4404
Thank you so much for these videos. I'm based in Australia and have watched 90 percent of your videos. As always, a great video. I'd like to introduce you and your viewers to my new channel, out of Australia. Fly Like a Girl - Fearless and Fabulous
awesome! We'll check it out.
I'm not convinced that Mike nor the purported Continental Experts have arrived at the full explanation as to why the Silicone and or Gasket Maker products when applied between the cylinder base to case deck results in a Cylinder Separation. I definitely believe that adherence to the PPT's set forth by the Manufacturer's assembly instructions are a suitable remedy and best practice. That said, I don't believe that the Explanation regarding the Cause as defined by the compression of or the Lack of compressibility of the sealer is the actual Cause of the fasteners failures. I struggled a bit juggling with metallurgy of both the Fasteners and Case / Cylinders trying to validate this " Loss of Security - Secure Fitment and various torque, twisting, stretching scenarios only too return back to; Nope! The only true explanation must be outside this obvious mechanical question. What Mike said sbout Silicone being slightly worse than the Gasket Maker in readily resulting in Cylinder Seperation really rang true and helped narrow the question to this being a Non Mechanical Failure Mode. IMHO The Solution is somewhat inadequate because there is likely to be another episode revolving around this Sealer Application. I'm itching to know if anyone ay Continental truly has the answer.🤔
How about you just follow the best practices manual by Continental and stop with the theoretical/hypothetical how many angels dance on the tip of a pin.
There is a better alternative for silk thread as the crankcase halves actually. It's a Loctite 515, but another problem I see (and there is warning in the manual...) if you use the 515, you're not supposed to use Silk!!!!!
@@DylanClements98Well, 515 is more practical than silk, and it has been working fine here. But yes... It's not that much better...
Still not conclusive as to the root cause of the failure! Possible misalignment of the cylinder or latent faulty through stud? Something more in depth would be the root cause of the failure! Perhaps by happenstance, cylinder alignment with case by shear luck is not an issue or a fatigued or QA inspected (materials testing and certification) through stud(s).
The bigger the glob the better the job. LOL
I thought that was only in welding. LOL!
I strongly recommend all A&P mechanics attend the Continental factory training. Wouldn’t hurt for aircraft owners to attend also.
Is it free..?
@@meowmeow2759 No.
I don’t remember the cost. That was about 10 years ago.
Itd be nice, if it was affordable for the general population of GA mechanics. Only bet is if you are lucky enough to be sent there by the shop.
Why is the pilot at fault in the lawsuit?
Ah, later in episode Mike says it was for the direction chosen on landing. I’m a CA based pilot and definitely know about the vineyard situation, but if you weren’t it sure looks just like another green field
I remember A little dab'll do ya, they love to run their fingers through your hair. My dad had maybe 12 jars he reused to keep different things in on his work truck so he wouldn't need to run off to get something when he was at a customers home. I was near Salinas when I was drafted in 71, doing BCT at Fort Ord.
Some mechanic bad outside manual decisium, "in hopes to..." Don't innovate!
LOL RTFM!
10:40
Brylcreem, just a dab-ll-do-ya!
im 40