A buddy of mine who has his own plane sent this link to me knowing I would find it interesting due to the great similarities between air-cooled aviation engines and the ones in our cars.

It is long, but very informative. Touches on burnt valves, cylinder/case cracks, etc.

Teaser - the first 15 minutes or so explains why compression tests are close to worthless.


https://www.youtube.com/watch?v=4NnOYvOlMB8

Wow, LOTS of useful information. The huge eye opener for me is that compression test have NO RELATIONSHIP to how the engine is really running under operating temperature. All types of cracks in heads and cases proved to also be VERY interesting. I liked how they mapped out the heat ranges of a burnt valve and what they looked like.

Thanks Ken for the info.

Everyone should watch this.

What he is talking about is a airplane going through a annual inspection that requires a compression test even though the engine is running fine, in order to find any potential problems before a failure in mid flight.

This is not the same thing as using a compression test to diagnose a automotive engine that won't start or is running poorly. Or just to check the overall health of the engine.

but if you watch the video, you will learn a hell of a lot.

On the surface, aviation engines are far different in that if they fail, things fall from the sky and kill people. However, the vast majority of what is covered in the video is applicable to our engines.

thanks for posting this it is excellent

On the surface, aviation engines are far different in that if they fail, things fall from the sky and kill people. However, the vast majority of what is covered in the video is applicable to our engines.

Total bullshit.

Interesting bit, but in respect to his "compression" test discussion, he is talking leak down which is what is performed during aircraft engine inspections, but is typically referred to as a compression test in the aviation world.

As for basic compression test in the auto world, I've never had one not indicate a true problem be it rings, burned valves, or just a simple valve adjustment. As for leak down, I don't have much experience there...

You forgot the exceptional skill and cunning of the pilots and their God like ability to fly a bird made of metal through the sky

Is that what you meant Elloit?

I think his FAA inspection is due.....


and he's just cranky about it.

I have to confess that I have only watched the first 36 minutes so far, but I learned a lot that is applicable to our engines. Not sure why Elliot is calling , but I would welcome discussion on the subjects discussed. I see no fault in the physics presented by the video maker.

I made it two years in engineering school before switching majors, so I have more understanding of the materials presented than most florists. I see no fault in the guy's logic.

Bold and old? Only if you're Snoopy. Pilots keep u safe. And an interesting topic

I think it's the engine quitting killing everyone. Planes glide just fine. In fact most descents in a jet profile are at flight idle, from 150 miles out or more.

Correct, they will glide fine until you hit stall speed... And if it's a helo, no engine means it's auto rotation time and pray for the best...

Being a pilot (fixed wing and helo) and an operator and builder of air cooled plane engines, I would say there are many parallels between these two motors. The biggest thing in aero engines is you have a manufacturer that tells you how to operate and there is a lot of CYA written into the equation. And remember, the pilot has a mixture control in the cockpit. Add that to a generally poor understanding (and sometimes fear) on the case of most pilots, and the potential for much engine abuse exists. Then throw in a government regulatory body and you can imagine the BS that ensues.

Savvy pilots use EGT as the means of correctly setting mixture (actually AFR) for various operating regimes. The physics/thermodynamics that occur from there are identical in either engine

BTW, in an autorotation the glide may suck, but you do have the ability to land with zero airspeed and zero sink rate. That has some distinct advantages to gliding in at flying speed in a fixed wing

F16s glide like a brick. Engine mfgr that I worked for used to show cockpit video of an F16 pilot that lost oil pressure and then engine, to impress on the importance of reliability in a single engine jet. They scrambled an F18 to wingman him down into a fogged over airstrip. He basically fell onto the center of the runway in zero visibility by just sticking with the F18. Quite the clencher. Last thing you hear him say to the F18 pilot as he rolls to a stop, "I owe you a six-pack"!

I've only gotten about 4 minutes it after three tries, quitting each time when I got irritated by silly statements. No more, I don't even care what "conclusions" it finally comes to if they're based on that kind of logic.

A passenger jet in Canada and one that landed in the Azores proved they are not too bad as a glider.
But I bet it was one hell of a job getting the stains out of the seats.

Fucking Canadians always forgetting to fill up the bus...

When I got my A&P license, we rebuilt a 7 cylinder radial engine, and we used dope and fabric to recover a a wing surface....and I'm not that old..

Just saying, what they teach you is what is required to pass the FAA license test, which doesn't have much to do with actually working as an A&P.

Its been a very long time since I turned wrenches for money, and I found the video very informative, and useful.

EXACTLY!!

Your comment about engines failing and things falling from the sky and killing people is total

It was full when it left

Agree, but auto gyration is no guarantee of a safe landing, and outside of the military, I don't think it is well trained and refreshed on a regular basis. Nor is gliding into unimproved surface at 120+ knots in a commercial passenger jet a guarantee of a safe landing.

But that is neither here nor there, back to the matter at hand. My brother is an A&P of almost 35 years, still turning wrenches. His take on leak down tests (compression in their case), it is a useful tool but not a perfect tool. Everybody is entitled to their opinions.

Also agree that between manufacturer liability and government legislation for safety, maintenance requirements are likely stricter than need be. On the other hand, based on the junk I see on our roads, I sometimes wish we had more regulation on cars in regard to maintenance before one of them smacks me due to mechanical failure.

One was the other wasn't, the Gimli Glider was a metric to imperial conversion fuck-up.

Very interesting. Thanks for posting.

To quote the immortal Emil Faber or Faber College - "Knowledge is good."

Funny.

Very instructive video. Thank you for sharing.

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