(Piston) Engine Failure Rate: 1/3200 hrs, yikes!

[Dan Thomas]

mx induced failure.

Spell it out next time.
https://acronyms.thefreedictionary.com/MIF

 

[wanttaja]

mx induced failure.

The problem with maintenance-induced failures is that there's really no clues on how common they are.

About two and a half percent of my Cessna 172 accidents (1998-2021) are either factory-induced or maintenance-induced failures. About 8.2% of all the 172 accidents were due to mechanical issues, so roughly a third of them had a builder/maintainer issues.

The other two-thirds? We don't really know. Sure, some of them (maybe most of them) were related to prior maintenance, but there's no NTSB data to confirm it. Parts do wear, parts do break. You could consider it a maintenance error that the A&P should have caught it at the last annual, but, again, there's nothing proving that.

Ron Wanttaja

 

[Capt. Geoffrey Thorpe]

72.35% Of all statistics are made up on the spot.

 

[Daleandee]

72.35% Of all statistics are made up on the spot.

I thought I read that it was 73.25% ...

 

[hindsight2020]

The problem with maintenance-induced failures is that there's really no clues on how common they are.

About two and a half percent of my Cessna 172 accidents (1998-2021) are either factory-induced or maintenance-induced failures. About 8.2% of all the 172 accidents were due to mechanical issues, so roughly a third of them had a builder/maintainer issues.

The other two-thirds? We don't really know. Sure, some of them (maybe most of them) were related to prior maintenance, but there's no NTSB data to confirm it. Parts do wear, parts do break. You could consider it a maintenance error that the A&P should have caught it at the last annual, but, again, there's nothing proving that.

Ron Wanttaja

To be clear, I'm not bemoaning that as a grievance. That's just what it is, an affair replete in plausible deniability. I also get that means nothing when it comes to getting your money back, but it can mean something when it comes to making a participation risk assessment in the first place, which is what the OP appears to bring up for discussion.

To that end, I don't need criminal court burden of proof to arrive at the private conclusion that the plurality of the so-called mechanical unknowns do come from MIF, and pivot my behavior accordingly. I know what that means for me and my attitude towards the topic going forward, and that's all that matters.

Lastly, to clarify, I never argued nor do I feel the IA overseeing my annual signoffs would have been in a position to establish the fatigue condition of my case/jug fasteners. There's no legal quarrel here. I am nonetheless happy to no longer be beholden to that relationship.

I fully intend to vinyl wrap "hope's not a plan...but it's all I could afford!" to my replacement go-kart.

 

[Dan Thomas]

How about some stats on lack-of-maintenance-induced failures? I bet that number is considerably worse than maintenance-induced failures. If it's not, why do we bother with maintenance?

 

[Bell206]

The problem with maintenance-induced failures is that there's really no clues on how common they are.

Exactly. But one problem with tracking those events is they require a signature in the book to make the determination.

The problem is there are a number of pilot owners who are either too cheap or think having to get an A&P to perform maintenance is over rated so no write up gets made.

Once you have a possible mx induced event the 1st place they look is who did the last work, ie., who signed the book. Know of 3 events where the mechanic was called in but after some investigation it became obvious someone else performed the work.

In 2 cases the owner eventually copped a plea and had cert suspended. In the 3rd case no determination could be made so the last person to sign the book properly got A&P suspended even though there was photographic evidence work had been performed after his sign off.

Its a goat rope no matter how you look at it. But based on what I've seen you can take any percentage you apply to mx induced events and at least a third or better would be pilot mx induced events.

 

[Dan Thomas]

In the 3rd case no determination could be made so the last person to sign the book properly got A&P suspended even though there was photographic evidence work had been performed after his sign off.

And owners wonder why the A&P population is thinning. Dishonesty and lies will do that.

 

[wanttaja]

How about some stats on lack-of-maintenance-induced failures? I bet that number is considerably worse than maintenance-induced failures. If it's not, why do we bother with maintenance?

Actually, I did find about seven cases in the 172 accident list where the NTSB Investigator mentioned failure to overhaul the engine at the proper interval as a contributing factor. Doesn't mean there aren't more; doesn't mean there aren't a LOT more.

The question is, why are we so gods-damned blasé, about engine failures? People fly airplane a hundred, two hundred hours a year and have what seems to be an amazingly high rate of engine failure....at least, when you compare them to the cars they drive. I drive a car five times as much (by hours) as I drive, yet haven't had an engine failure (e.g. needed a tow) for 30+ years. Only problems I've had are failure to start, which by its very nature, is a relatively safe event.

Ron Wanttaja

 

[Tusayan]

I drive a car five times as much (by hours) as I drive, yet haven't had an engine failure (e.g. needed a tow) for 30+ years.

I had one this week, a failed air mass flow sensor on a 2017 car. That was fixed, then one injector replaced per the OBD, and now the Check Engine light still won’t stay out. More parts will likely need to be thrown at it, almost randomly and at great cost, until the OBD God is satisfied.

The last one before that was about 3 years ago, a shorting injector harness that caused massive misfire. High underhood temperatures were the root cause.

By comparison I’ll take maintaining an O-320 in reliable condition any time.

 

[Rockymountain]

My track record in planes is better than my track record in cars. Around 700,000 nm in aircraft, never having to push or get pulled. Been several in cars. Of course the car engine failures don’t end up in the news paper. I fly mostly new airplanes, and fly mostly new cars, so pretty much apples to apples.

 

[fast99]

There is one huge difference between auto engines and aircraft powerplants. Most of the time an auto engine is limping around at minimal throttle. Load one to 65% not a chance it will make 2000 hours.

Closer comparison would be a boat. They have an endless supply of coolant and run at 140 degrees. Have never seen a gas marine engine get to 1000 hours.

Haven't automotive engines been adapted to aircraft? How long do those last?

 

[infrequentFlyer]

Closer comparison would be a boat.

Or a 1950s VW bug. Air cooled, carbureted, and designed over 70 years ago just like our trusty O-320s. They were even horizonally opposed.

Apparently aircraft with Beatle engines are a thing too.

 

[fast99]

Good point, a VW usually isn't loaded hard for long periods, although I did lay the throttle on the floor of a 64 bug for about 300 miles once, about 5 hours.

 

[Dan Thomas]

Apparently aircraft with Beatle engines are a thing too.

And have been since the 1960s, at least. They have been much modified and there are aftermarket manufacturers that make the entire thing, with displacements to 2 litres and beyond, pumping out 80 HP.

But they were not originally designed as an aircraft engine. The O-320 was. The VW's chief shortcoming is the lack of sufficient cooling fins on the head, leading to burned valves. Another one was breaking of the original crankshafts, fixed by using aftermarket shafts designed to take the high thrust and gyroscopic precession loads.

 

[Ed Haywood]

Pilots like to look at statistics and accident reports so they can justify to themselves that it must have been the pilot or there was something they would have done different if it was them. Almost every pilot in an accident thought before takeoff “it wouldn’t happen to me. I’m a better /more careful /more experienced pilot than average”. Yet statistics show that just isn’t true. You will face an in flight emergency if you fly enough and there is a possibility you may die because of it. We can do things like recurrent training and keeping up on maintenance to try and tip the scales a little more in our favor but the truth is that flying is risky and every time you go up there is always a chance you may not come back. The best you can do is make sure you are proficient enough to not make an emergency any worse than it needs to be. An engine failure isn’t a death sentence but trying to stretch a glide to the airport and stalling it in after the engine failed sure is.

Was thinking about this yesterday as I strapped up to fly aerobatics. People have different levels of tolerance to cognitive dissonance. Some pilots cannot hold two contradictory thoughts in their mind, and try to reconcile the conflict. IMO you can never be too well trained or maintained, but you are still doing something inherently dangerous and may well die from it.
What I chuckle at are guys who think they can eliminate risk if they are just careful enough. That manifests itself in things like overly fussy preflight inspections focused on superficial exterior issues.
Having said that, I think too many GA pilots outsource maintenance to their A&P to their detriment. Maintenance is portrayed as a dark art that only federally licensed wizards are allowed to partake in. In reality, it doesn’t take an aircraft systems engineer to spot many problems. A little proactive checking under the hood can drastically reduce the risk of certain failure modes.
A good example would be oil hoses. A certain percentage of engine failures are due to oil starvation. There are a finite number of orifices from which oil can depart an engine. How many pilot owners keep their engines spotless so they can immediately spot a leak? How many regularly inspect their hoses for signs of deterioration, and replace on a timeline? How many pilots know which fittings should be safetied, and check those? How many use torque seal?

 

[infrequentFlyer]

But they were not originally designed as an aircraft engine. The O-320 was.

Gotchya - I wasn't trying to compare VW engines in a plane to similar era aircraft engines in a plane. I was saying an O-320 compared to any modern engine is apples and tomatoes.

No matter how much better the O-320 is at cooling than a VW or how much more reinforced tha crankshaft is, it still relies on variable passive airflow for cooling, imprecise fuel delivery resulting in non-ideal combustion chamber temps/air-fuel mixtures, and lacks features like knock sensors which prevent you from being able to see through a hole in the top of your piston after a hard days work.

Modern engines are more reliable, and an O-320 just isn't in the same league. Not to mention many impending failures are monitored by your car - you will get an alert with enough time to at least pull over, or often times drive for several thousand more miles before fixing. That is, unless you drive a 1950s beatle

 

[Dan Thomas]

No matter how much better the O-320 is at cooling than a VW or how much more reinforced tha crankshaft is, it still relies on variable passive airflow for cooling, imprecise fuel delivery resulting in non-ideal combustion chamber temps/air-fuel mixtures, and lacks features like knock sensors which prevent you from being able to see through a hole in the top of your piston after a hard days work.

Nothing passive about the cooling. The system is engineered to work adequately, and it avoids the weight and risk of loss of liquid coolants. It also gets more airflow when the RPM, and therefore relative power and waste heat, is higher.

Yes, the fuel delivery, especially for carbed systems, is a bit rough, but in many (most) of those engines I have flown, the mixtures have been so even between cylinders that the RPM falls without vibration when I lean that engine. Roughness would indicate uneven distribution. Aircraft fuel injection is far better, especially with the GAMI nozzles designed for particular engines. Even Continental sends out their engines now with such nozzles.

Knock sensors are not required if the engine is operated within POH/AFM parameters and the correct fuel is used. These engines aren't the 10:1+ compression-ratio engines found in cars now. CRs are much lower for most.

 

[infrequentFlyer]

Nothing passive about the cooling. The system is engineered to work adequately, and it avoids the weight and risk of loss of liquid coolants. It also gets more airflow when the RPM, and therefore relative power and waste heat, is higher.

Yes, the fuel delivery, especially for carbed systems, is a bit rough, but in many (most) of those engines I have flown, the mixtures have been so even between cylinders that the RPM falls without vibration when I lean that engine. Roughness would indicate uneven distribution. Aircraft fuel injection is far better, especially with the GAMI nozzles designed for particular engines. Even Continental sends out their engines now with such nozzles.

Knock sensors are not required if the engine is operated within POH/AFM parameters and the correct fuel is used. These engines aren't the 10:1+ compression-ratio engines found in cars now. CRs are much lower for most.

Not sure what your point is - you think that an O-320 is as reliable as a Corolla 4-cylinder?

They (a/c pistons engines) are simple and good for the job - I never said they weren't. I maintain that the modern add-ons of your daily driver make that engine more dependable. That's all I was saying to begin with.

 

[Dan Thomas]

Not sure what your point is - you think that an O-320 is as reliable as a Corolla 4-cylinder?

They (a/c pistons engines) are simple and good for the job - I never said they weren't. I maintain that the modern add-ons of your daily driver make that engine more dependable. That's all I was saying to begin with.

The O-320 is indeed as reliable as the Corolla's engine. It is designed to put out full power for its entire TBO of 2000 hours. At 130 MPH, that's 260,000 miles. And when it is torn down, if it received proper oil changes, it will still be good for another 1500 hours. There are 320s with well over 4000 hours on them.

The 320 has magnetos, and most have carbs. Magnetos are still being used because they do not rely on the aircraft's electrical system. Carbs, same thing. When I was in Power Mechanics in high school in 1967 or so, the instructor told us that 90% of engine troubles were electrical, not mechanical. And in all those years since then, I have found that he was absolutely right. In all the vehicles I owned, the electrical system gave the most trouble. Generators or alternators, distributor (whether points-and-condenser or electronic) all suffered from wear, vibration, heat and cold, age, corrosion and the like. And when anything in the system that feeds the electronic ignition or electronic fuel injection fails, the car's engine quits dead. Even the simple in-tank fuel pumps for the injection system are famous for going AWOL.

Sure, there are airplanes with EI and EFI, but the safe ones (and all the certified ones) have backup electrical systems, whether it's a separate second alternator and battery or just a battery, and separate supply buses, just to keep things running. Lycoming has its certified iE2 engine that has EI and EFI plus backup systems, but it isn't cheap. Cheap and safe just don't go together. It's a major reason why flying is expensive, after all.

 

[infrequentFlyer]

The O-320 is indeed as reliable as the Corolla's engine. It is designed to put out full power for its entire TBO of 2000 hours. At 130 MPH, that's 260,000 miles. And when it is torn down, if it received proper oil changes, it will still be good for another 1500 hours. There are 320s with well over 4000 hours on them.

The 320 has magnetos, and most have carbs. Magnetos are still being used because they do not rely on the aircraft's electrical system. Carbs, same thing. When I was in Power Mechanics in high school in 1967 or so, the instructor told us that 90% of engine troubles were electrical, not mechanical. And in all those years since then, I have found that he was absolutely right. In all the vehicles I owned, the electrical system gave the most trouble. Generators or alternators, distributor (whether points-and-condenser or electronic) all suffered from wear, vibration, heat and cold, age, corrosion and the like. And when anything in the system that feeds the electronic ignition or electronic fuel injection fails, the car's engine quits dead.

Sure, there are airplanes with EI and EFI, but the safe ones (and all the certified ones) have backup electrical systems, whether it's a separate second alternator and battery or just a battery, and separate supply buses, just to keep things running. Lycoming has its iE2 engine that has EI and EFI plus backup systems, but it isn't cheap. Cheap and safe just don't go together. It's a major reason why flying is expensive, after all.

Let's make a distinction between two things which you are combining:

Is O-320 reliable - compared to it's peers? I'm not saying anything about this question, because I don't know much about the engine compared to it's peers. So I can't respond to anything you say on this.

Is O-320 as reliable as modern engine? This I do know the answer to, and sorry to disappoint, but it is not. If you want to disagree the burden is on you, because knock sensors, O2 sensors, airflow sensors, ambient air temperatures, cylinder misfire sensors, all feed into a computer which manages air fuel mixture better than the red baron. This has resulted in automotive engine breakdowns becoming basically a non-issue.

Carbureted oil cooled engines are inefficient and prone to poor combustion when compared to the modern alternative. Remember, I'm comparing to the modern alternative, not making a objective statement about the engine.

Have you ever driven a carbureted car? Started a lawnmower in the spring? Unless I'm missing something fundamentally different about a/c carburetors, oil coolers, and aluminum fins then they are indeed NOT as reliable as a Corolla.

To summarize: 2020 tech is better than 1950's. Duh.

 

[Bell206]

Maintenance is portrayed as a dark art that only federally licensed wizards are allowed to partake in.

FWIW: I dont think its driven by mystery at all. To me it simply boils down to person themselves whether they want to work on their aircraft.

I general terms, 50% of private GA owners simply dont want the work or dont like the work or dont have the opportunity to perform the work. The next 25% are all in and will attempt and conquer any job on their aircraft whether prevent mx items or working under an A&P similar to what you did.

The last 25% are the owners who try to beat the system when ever they can with the bottom 10% fans of $200 dollar annuals, hangar fairies, etc.

The main hurdle for those in the 50% group who want to try is education and/or someone to show them the ropes. Half of my past owner-assist customers came from the 50 group and the other half from the 25 group who wanted to expand their horizons.

So in my book its the person and not the "rumor" that controls who works on their own aircraft.

 

[Half Fast]

Let's make a distinction between two things which you are combining:

Is O-320 reliable - compared to it's peers? I'm not saying anything about this question, because I don't know much about the engine compared to it's peers. So I can't respond to anything you say on this.

Is O-320 as reliable as modern engine? This I do know the answer to, and sorry to disappoint, but it is not. If you want to disagree the burden is on you, because knock sensors, O2 sensors, airflow sensors, ambient air temperatures, cylinder misfire sensors, all feed into a computer which manages air fuel mixture better than the red baron. This has resulted in automotive engine breakdowns becoming basically a non-issue.

Carbureted oil cooled engines are inefficient and prone to poor combustion when compared to the modern alternative. Remember, I'm comparing to the modern alternative, not making a objective statement about the engine.

Have you ever driven a carbureted car? Started a lawnmower in the spring? Unless I'm missing something fundamentally different about a/c carburetors, oil coolers, and aluminum fins then they are indeed NOT as reliable as a Corolla.

To summarize: 2020 tech is better than 1950's. Duh.

I beg to differ.

My MINI stranded me at 80k miles when the water pump failed.

Then a little past 100k miles it stranded me when the timing chain tensioner bolt failed and created a massive oil leak.

Then at 120k miles the turbo failed.

Finally at 150k the timing chain broke, allowing a piston to punch a valve. I scrapped the car at that point, as a new engine cost more than the value of the car.

(And that’s why I will NEVER own another BMW product, by the way.)

 

[Rockymountain]

If automobile engines were powerful enough and reliable enough to work in planes the OEM’s would have switched long ago. But they aren’t. You run a car engine like a plane engine at high power, low altitude, high altitude, outside air temp changing 30-40 degrees every flight, and they will grenade. The closest we have seen were the Thielert diesels, which were an utter disaster for diamond. The Mercedes converted Austro’s are better, but certainly not as powerful or as light as their gas powered counterparts, and have not been proven to be more reliable. A lot of diamond diesels have landed off field. One just burned up in Spanish fork Utah after an emergency landing. And nothing in the automotive world even comes anywhere close to a turbine in power to weight and reliability. So one day car engines may catch up to airplane engines, but they haven’t yet.

 

[Daleandee]

If automobile engines were powerful enough and reliable enough to work in planes the OEM’s would have switched long ago. But they aren’t. You run a car engine like a plane engine at high power, low altitude, high altitude, outside air temp changing 30-40 degrees every flight, and they will grenade. The closest we have seen were the Thielert diesels, which were an utter disaster for diamond. The Mercedes converted Austro’s are better, but certainly not as powerful or as light as their gas powered counterparts, and have not been proven to be more reliable. A lot of diamond diesels have landed off field. One just burned up in Spanish fork Utah after an emergency landing. And nothing in the automotive world even comes anywhere close to a turbine in power to weight and reliability. So one day car engines may catch up to airplane engines, but they haven’t yet.

https://www.caranddriver.com/news/a15366911/how-powertrain-development-teams-ensure-durability-by-beating-the-crap-out-of-engines/

Ford is pretty tough on testing:

 

[Ashara Keliyn]

I don't know, almost 400k miles on my original engine 2000 4runner. NEVER had any repairs done on the engine (other than change spark plugs). Leaks very little oil, and frankly, there were more than few missed oil changes and deferred maintenance. The only issue was failed alternator back when it was still under warranty. Plan on reaching 500k. Those engines are legendary and have the perfect balance of old and new tech.

 

[2-Bit Speed]

I don't know, almost 400k miles on my original engine 2000 4runner. NEVER had any repairs done on the engine (other than change spark plugs). Leaks very little oil, and frankly, there were more than few missed oil changes and deferred maintenance. The only issue was failed alternator back when it was still under warranty. Plan on reaching 500k. Those engines are legendary and have the perfect balance of old and new tech.

Just remember that averages have no power over individuals.

 

[infrequentFlyer]

My MINI stranded me at 80k miles when the water pump failed.

Then a little past 100k miles it stranded me when the timing chain tensioner bolt failed and created a massive oil leak.

Then at 120k miles the turbo failed.

Finally at 150k the timing chain broke, allowing a piston to punch a valve. I scrapped the car at that point, as a new engine cost more than the value of the car.

See 2-bit's response below:

Just remember that averages have no power over individuals.

... And I have hears stories about the Mini's - the engines are indeed notorious.

You run a car engine like a plane engine at high power, low altitude, high altitude, outside air temp changing 30-40 degrees every flight, and they will grenade.

Why?

And nothing in the automotive world even comes anywhere close to a turbine in power to weight and reliability.

We're not talking about turbines.

Let's leave a/c out of the question for a second: are modern automobile engines more reliable than their 1950s counterparts? Why?

 

[Dan Thomas]

Is O-320 as reliable as modern engine? This I do know the answer to, and sorry to disappoint, but it is not. If you want to disagree the burden is on you, because knock sensors, O2 sensors, airflow sensors, ambient air temperatures, cylinder misfire sensors, all feed into a computer which manages air fuel mixture better than the red baron. This has resulted in automotive engine breakdowns becoming basically a non-issue.

Carbureted oil cooled engines are inefficient and prone to poor combustion when compared to the modern alternative. Remember, I'm comparing to the modern alternative, not making a objective statement about the engine.

Have you ever driven a carbureted car? Started a lawnmower in the spring? Unless I'm missing something fundamentally different about a/c carburetors, oil coolers, and aluminum fins then they are indeed NOT as reliable as a Corolla.

To summarize: 2020 tech is better than 1950's. Duh.

The O-320 doesn't come apart, as in throw a rod or something unless there was a serious flaw in its manufacture, or it had a propstrike that was never addressed. Or the pilot never checked the oil, using the airplane as he did his car, and it ran out of oil and blew up.

Aircraft engine components get non-destructive inspection, something that car engines don't get. The aircraft engine failures are pretty much always due to ancillary systems like magnetos or the fuel system, both being improperly maintained, or not maintained at all.

The efficiency of the engine using EI and EFI has NOTHING to do with reliability, and that is what this argument is about. Sure, EI and EFI make the engine more efficient. They don't make it more reliable, for the electrical reasons I posted earlier. Yes, 2020 tech is better than 1950s tech, but to apply it to an aircraft engine, you had better know what you are doing. There have been too many accidents when the fancy stuff quit on the homebuilder. As I pointed out, Lycoming has done it, and it works, but it requires backup systems and it costs way more. You can have it if you have the cash.

A huge percentage of engine failures are due to carb ice. There are investigations that find nothing wrong with the failed engine, and it might even run fine afterward. The accident took place in a time and place where the environmental conditions were conducive to carb icing. But pilots are not being properly taught about carb ice and why and how it forms, and how to handle it. That's not the engine's problem. That's the pilot's.

The only issue was failed alternator back when it was still under warranty. Plan on reaching 500k.

Exactly what I was saying. That alternator feeds EVERY electrical item in that car, and if it quits, the battery isn't going to last long at all. The EI and EFI alone take a bunch of amps. All the fancy sensors and stuff take some more. Alternators have field brushes in them that carry the field current to the rotor winding, and when a brush fails by wearing out, the field goes dead and the alternator produces nothing.

In both cars and airplanes, the alternator's belt and pulleys, or gears, are designed so that the alternator reaches redline when the engine reaches redline. That protects the alternator from overspeed while letting it produce its max power. In the car that has a 6500 RPM redline, the engine is typically cruising at 2000 or 2500 RPM, so the alternator's speed is maybe a third of its redline. In the airplane, an engine like the O-320 that has a 2700 RPM redline will cruise at 2500, sometimes 2600, and that alternator is real close to redline for most of its life, so those brushes wear out far sooner. So we see manufacturer recommendations that the alternator be taken off and opened up every 500 hours for a brush inspection. I typically found them 1/3 toward the limit at 500, and 2/3 at 1000, and I sure wasn't going to try to get another 500 hours out of a set of $20 brushes. I would say that most aircraft alternators are being run to failure, not getting those brush inspections. Here on POA we see a fairly steady stream of alternator-failure stories. No need for that. If a brush wears past limits and pops out of its holder, the spring behind it arcs on the rotor slip ring, destroying it, meaning a new alternator instead of a quick inspection and brush replacement. Is that economical and safe??

A Corolla engine in an airplane will eat up its alternator just as fast, and everything will die with no backup. An O-320 will keep running, but the lights and radios poop out soon enough. Bad deal at night or in IMC.

Let's leave a/c out of the question for a second: are modern automobile engines more reliable than their 1950s counterparts? Why?

If the 1950 car was properly maintained, and that didn't take a lot of work, it ran fine until it just wore right out. Keep the carb and filters clean. Replace the points and condenser and plugs every 12K miles or so. Keep the generator brushes in good shape. And that engine would run forever. What it didn't do was run far beyond 100K miles without wearing out, and that was due to the lubricants of the time (no synthetics) and the older metallurgy. New aircraft engines are using synthetic oils and new metallurgy just like modern cars.

My Continental A-65, built in 1946, has hydraulic valve lifters. Cars didn't get those for about 15 more years, or more. Mechanical fuel injection was available in some Chevys in the 1950s, after aircraft had been using it for some time. Turbo- and superchargers were used during WW2, 60 years before they became common in cars.

See, the whole "Lycont dinosaur engine" is a myth. If those engines were so unreliable, we'd see all airplanes with engines failing by 3200 hours, as per the stats posted early in this thread. But we have airplanes with 30K hours on them, and no failures. We have airplanes built in the late 1930s that have had no failures.

 

[Bell206]

This has resulted in automotive engine breakdowns becoming basically a non-issue.

The one thing you leave out in this discussion that is usually part of the auto engine vs aircraft engine debate are the international aviation certification requirements. And as discussed in detail in other PoA threads one the hardest certification requirement for a "modern" auto engine to pass are the fire prevention tests.

Also reliability has many definitions all controlled by the context of that definition. For example, Lycoming and Continental have a very good reliability record for aircraft engines. Regardless, while auto engines appear like they offer plenty of advantages on the surface you'll find those advantages quickly disappear once you dig a little deeper. Even Toyota and Porche found this out with their venture into aviation engines using existing models of their car engines back in the 80s and 90s but couldn't compete with Lyco or TCM. It is what it is.

 

[Mikey52]

What ever happened to the Porsche powered Mooney?

 

[infrequentFlyer]

EFI + water cooling BOTH contribute to engine longevity by maintaining constant combustion chamber temps. If you don't believe me look at the valves on any carb'd engine vs. any engine with EFI + water cooling. I have no idea what EI is.

Add EFI and water cooling to a lycoming and your TBO will increase. You don't burn valves. Your cylinders wear out less (because constant temps, not metallurgy). You will do better with cold/hot fluctuations despite what Rockymountain believes, because your engine will remain at a more constant temp via thermostat. OAT no longer matters as much.

Also, as you pointed out, human factors result in many engine failures. Your going to the ground whether it's your fault or not. But this is a bit of a cheat argument since I said the engines were more reliable, so I won't count it. Worth pointing out as a fringe benefit though.

More advanced = more points of failure - I agree. Have to make the parts more robust and just like you pointed out that a/c engines are already more robust. This is a sticking point since I don't know how much "more robust" they can be made, but I believe it will be an improvement nonetheless. Car parts are made to be cheap first, reliable second. The other way once you start making for a/c.

My Continental A-65, built in 1946, has hydraulic valve lifters. Cars didn't get those for about 15 more years, or more. Mechanical fuel injection was available in some Chevys in the 1950s, after aircraft had been using it for some time. Turbo- and superchargers were used during WW2, 60 years before they became common in cars.

I think this whole thing started talking about 172s. I didn't say there "aren't" advanced a/c engines. But the engine in my trainer IS a dinosaur and that's no myth. Turbos are a huge point of failure in autos. Are they reliable in a/c? If so then I bet they can make other parts more reliable too.

Enjoying the discussion despite our disagreement! But I am running out of breath a little bit.

 

[Dan Thomas]

What ever happened to the Porsche powered Mooney?

From Wiki:

After being introduced in late 1985 and starting to generate increasing interest in the general aviation (GA) market, Porsche exited the field during the massive downturn in the market in the late 1980s, closing the lines in 1991. It is suggested that the program cost it US$75 million to develop and produce the small number of engines delivered (about 80).

Aircraft engines are not cheap to develop. In 2010 I worked on one of the 50 SMA SR-305 diesel engines that were flying at that time worldwide, after SMA had sunk a billion dollars into the program. They are understandably expensive, and few are seen anywhere in North America. They are more in use in Africa, where avgas can be $10+ per litre. No refineries in Africa produce avgas; it has to be shipped in, and since Africa is a huge continent, and roads are often sketchy, trucking is expensive too. Aircraft with turbine engines need Jet fuel, and there are also a lot of diesel vehicles there, so the refineries make lots of both. The SMA uses Jet A.

 

[Dan Thomas]

I have no idea what EI is.

Electronic ignition.

I am not speaking from ignorance re auto engines. I did the engineering and installation of a Subaru 2.2 litre (EJ22) in a Glastar in the 1990s. RAF redrive, Ford electronic ignition, carburetor. There is no provision on the engine for a mechanical fuel pump (as found on aircraft engines) so it had to have TWO electric fuel pumps to make sure the engine got enough fuel if one failed. The only electrical backup was the battery, so run time after alternator failure was very limited.

I used the full-size radiator from the car, making a plenum behind the engine so that all cooling air coming in the cowl had to exit through that plenum and through the radiator. In an extended climb, coolant temps reached 230°F. Cooling in many homebuilt conversions is a weak point, and overheating is a real problem. I managed to hide this whole system inside the cowling, where some others are found outside in the breeze, creating drag.

The Holley carb was modified to have a mixture control. One day, to test short-field takeoff capability, I locked the brakes, ran the engine to full throttle, and leaned for max RPM, all SOP for short-field stuff in TC'd aircraft. Took off, and at 200 feet I lost a cylinder. An exhaust valve had burned. I took the head off, and found that those valves were hardly any bigger than one would find in a Briggs and Stratton lawnmower engine. Four-valve cylinders. That engine had had EFI in the car, and the computer would enrich the mix to prevent that at high power. A Lycoming or Continental has massive exhaust valves with thick stems, sodium-filled for cooling, thick heads, and made from expensive exotic alloys. One can run that engine to full throttle and best power mix without hurting them. In the Soob, you need that 40 pounds of computer and wiring harnesses and EFI stuff to prevent burnout of light stuff.

Russ at SDS makes EI and EFI stuff for converted Soobs as well as Lycs and Continentals. It protects stuff.
Works well.

You can think of your trainer engine as a dinosaur, but you don't have much choice, do you? You're stuck with it, just like every other owner of a certified airplane, so you'd better learn everything you can about it and learn to operate it safely. It will not forgive much ignorance. Calling these things dinosaurs will not get better engines to market, considering the expensive failures of Honda, Toyota, Porsche, SMA (though it IS flying), so not a failure, just a failure to produce a much cheaper and more reliable engine; it also has liquid-cooled heads), Thielert's Centurion, Continental's liquid-cooled Voyager, and even Continental's Tiara engine. We have what we have, and there are good reasons for that. The R&D of legacy engines was paid off long ago, a bunch of it by the military, and incremental improvements are affordable. Entirely new engines are not.

 

[infrequentFlyer]

Have a nice day, this is clearly going nowhere. Stand by all my points 100% and don't care if you built an experimental which failed. I never said use a car engine for an a/c for the reasons you said earlier.

 

[Ed Haywood]

Add EFI and water cooling to a lycoming and your TBO will increase.

Add water cooling to a Lycoming and you will get reduced flight performance due to added weight. You will also lose aircraft to in-flight engine failures caused by coolant system compromise.

I see cars broken down on the side of the road all the time. It is almost always overheating due to loss of coolant. Hoses burst, radiators leak, water pumps seize up. If that happens in flight, you are coming down.

If water cooled engines were superior to Lycs and Conti's for aviation, they would be used instead.

 

[2-Bit Speed]

If water cooled engines were superior to Lycs and Conti's for aviation, they would be used instead.

I am very curious about this. In WW2, fighters used both types of engine. The main advantage of the liquid-cooled engines was fuel economy (it certainly wasn't durability). Air-cooled powered planes could go just as fast and just as high, but they used more fuel to do it.

It seems like there must be a point at which liquid-cooled engines produce less drag than air-cooled engines, but I don't know where that point is. If there is such a point, that performance level would probably be the bread-and-butter of turbine aircraft, rendering all of this purely academic.

 

[Dan Thomas]

I am very curious about this. In WW2, fighters used both types of engine. The main advantage of the liquid-cooled engines was fuel economy (it certainly wasn't durability). Air-cooled powered planes could go just as fast and just as high, but they used more fuel to do it.

It seems like there must be a point at which liquid-cooled engines produce less drag than air-cooled engines, but I don't know where that point is. If there is such a point, that performance level would probably be the bread-and-butter of turbine aircraft, rendering all of this purely academic.

Engines like the Allison and Merlin V-12s were liquid-cooled to reduce profile drag (radials can have a LOT of that) and to get as much HP out of limited cubic inches as possible. But those airplanes needed some very cleverly-designed coolant systems to reduce cooling drag, and yet they were still often brought down by one bullet hole through a rad or coolant pipe.

 

[2-Bit Speed]

Engines like the Allison and Merlin V-12s were liquid-cooled to reduce profile drag (radials can have a LOT of that) and to get as much HP out of limited cubic inches as possible.

Which is precisely my point. There must be level of power beyond which a liquid cooled engine produces less drag than an air-cooled engine and that that power level is currently occupied by turbines.

 

[Hang 4]

My 2 cents. Aircraft engines have relatively large bore and stroke compared to an automotive engine. All this weight tossing back and forth on top of relatively loose clearances make for a ton of vibration and pretty enormous forces on the bearings, case etc. Yes it's counterbalanced, but it's still a lot of mass accelerating and decelerating. It's also slinging around a giant propeller that not everyone gets dynamically balanced.

Compare this with a solid block modern engine where they run at much higher RPM to produce a given HP, but with a much shorter stroke. Even a Porsche 911 engine (the old air-cooled versions) have 74mm stroke vs 111mm for a Lycoming O360. They are each 180hp, but the Porsche (911SC) produces that at 5,500 rpm vs half that for the Lycoming. Those weren't exactly known for long wear either, but it's a more like to like than a V8. Move to the solid block engines and all this gets even smoother for the automotive engine. Shorter stroke, inline or V engine configuration and it's a much easier life.

I don't see anything changing in the aircraft side unless Rotax keeps moving up the foodchain.