Engine out!

[ceo_of_the_sofa]

Anyone care to enlighten the lesser learned of us here a bit more on the engine outs (in airplanes)?
Here are some questions I have for you, pros:
Considering every airplane engine is almost build by hand, checked and double checked to the highest measure of the applicable law (I hope) and has a mandatory overhaul period...there still seems to be a very high rate of engine failures(per hours flown vs. car engine hours).
In all my years of driving (and I drive a lot) never once has the engine quit on me (multiple vehicles, of various vintages, some maintaned well, some not). There was a Civic in my past, which I personally put 150,000 miles on, and it was kind of hard to start in the end, but it wouldn't just quit...
What gives?
And since we're on the topic...Do recips just quit, or is it a more gradual process? Obviously, in a case of a crank breaking in half, it'll probably just stop...

 

[abatista]

Well let’s see if you use the time of a normal engine for C172 0-320. It will give you 2000 hours of use.

If normal cruise is 105 knots = about 120mhp. This will give you about 240,000 miles. So if you fly on this engine only 1000 hours you will get 120,000 miles. We change the oil on them every 50 hours or every 6000 miles. Now this is just a quick not exact calculation on my part.

As you can see they do last longer then most Car engines. And the main problem with failure is due to poor maintenance, improper fuel, or other items. It's not everyday you see it fail due to a cylinder when bad. Another failure that happens to them is the fuel pump. I feel that these engines do last along time. There are good engines that are made to last a long time.

 

[ceo_of_the_sofa]

Very good point, I agree, but what about car engines having to deal with constantly changing power settings, and sometimes operating past their limitations (unlike aircraft engines, which are limited by de-rating)?

 

[Wiggums]

Well for one thing, engine changes aren’t as mandatory as you may think. Under Part 91 operations you can keep running an engine as long as a mechanic will sign off on it at the annual or hundred hour inspection. I’ve seen plenty of engines at flight schools with over 3000 hours that run ok. Most signs of failure can be caught before the engine actually fails. Some clues are low compression, excessive oil burning, less power, or unusually high amount of certain metals found by oil analysis.

Most engine failures are not even the fault the engine. Fuel starvation is the number cause of engine outs. If you keep enough gas on the aircraft your chances of an engine failure go way down. Many other failures are caused by poor or no maintenance. Even if you do have an actual mechanical failure, in many cases you can nurse the thing to an airport. An engine that sucked a valve or burned a cylinder doesn’t just quit. Aircraft engines are much better built then car engines, and can take quite a large amount of abuse.

In comparison to aircraft engines, car engines have a much easier life. First of all, with an aircraft engine you demand 100% power of a few minutes at takeoff, then usually run the thing a continuous setting of around 65%-75%. A car engine rarely runs this hard for so long. I’d bet a civic cruising down the highway needs less then 20hp to maintain speed. Even when you demand 100% from a car engine it is only for a short duration. Car engines are water cooled, so they operate at a very constant temperature, unlike an aircraft engine that can easily be shock cooled. Lastly, car engines have ECU that protect the engine by doing things like setting the mixture and not allowing the RPMs to exceed redline.

I do believe aircraft engines should incorporate some of the technology the car industry uses. My ideal engine would be a liquid-cooled, supercharged diesel engine with FADEC.

 

[ceo_of_the_sofa]

Yes, diesel does seem like an ideal powerplant for an aircraft, as they tend to run better with a constant power setting (i.e. as generators, etc) It's weight though, would probably be a little problematic in incorporating in the aircraft design. Since compression is so much higher in diesels, they have to beef up components at the expense of weight. Not an issue with a BobKat, but probably a problem with an airplane?

 

[Wiggums]

Check this diesel engine that is a good candidate to replace Lycomming O-320s. Installed it only weighs a few more pounds then an O-320. Those few pounds are easily offset by the fact that you won't have to carry as much fuel to complete the same mission as you would for the Lycomming engine, so your overall takeoff weight would be lower.

One other advantage of a diesel engine is that it burns JET-A, which in the future will be around, unlike avgas which has a bleaker future.

 

[100LL... Again!]

Check out the Zoche diesel engine - from Germany - very cool.

 

[bugchaser]

I have to admit that I have had my fair share of engine troubles. Broken cranks, busted cases, bearing failures, and many broken jugs. On the flat engines such as the 520 etc., they will almost always get you home unless a bearing, crank or rod fails. I have had 2 bearing failures and both times the engine simply went from running strong to stopped in a few seconds. With a busted cylinder, you can usually make enough power to get home. As was stated earlier, most engine out incidents have to do with fuel starvation. The radial engines are a different deal. Many times a broken cylinder will put you down very quickly. It is very common for this to happen with the old round engines. I had one last summer that blew the head completely off. Nedless to say, it did not run very well after that. As for high time engines, it is very possible for a well maintained engine to go way beyond TBO without any problems. Usually the engine will get a little weak on compression etc., but that does not mean that it will have a major part break. Honestly, I am most nervous when sitting behind a new engine. If it makes it past a few hundred hours, it will probably be OK. Sorry for rambling, just my 2 cents.

 

[SkyWestCRJPilot]

If you're going to compare auto engines and airplane engines then you need to be comparing Formula 1 engines with airplane engines. They run at close to 100% power for long durations like airplane engines do. Your car engine runs at about 15% power on the highway. To run your car at 100% power you'd have to rev it up to just below redline and maintain that. At the Reno air races they fly those airplanes at 100% power the whole race knowing that the engine is shot after the race is over. They just hope the engine will last long enough to finish the race. Formula 1 engines are the same, shot after the race. The Chieftain I flew with two TIO-540 Lycomings had a turbocharger for each engine that increased manifold pressure to 44 inches on takeoff. In cruise at night you could see the pipe from the turbocharger glowing red hot through vents in the cowling. I bet most of your average car engines don't glow red hot when you drive them at night. Others have stated other good reasons for aircraft engine failures like air cooled instead of liquid cooled. You mentioned derating engines. Some are but not all and derating does allow an engine to last longer before overhaul. Jet engines on the other hand hardly ever fail. They have very few moving parts so there is not much to break.

 

[KigAir]

Hey ceo_of_the_sofa I hate to say this but Fly Chicgao's avitar's is better.

 

[Kingairrick]

WHAT THE????

Deftone:

No offense, but I'd be afraid to get into an airplane with you if your luck is still the same...I almost pissed myself reading that scene....its like something from a movie.