how reliable are Lycoming motors?

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Carl Hammie

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Carl Hammie
Hello, I have a buddy who owns an airplane with a 360 cubic inch Lycoming. I have never been in a small plane and I wonder how reliable these motors are?

Carl
 
The Lycoming 360 is one of the most prolific workhorses of the aviation world. The list of aircraft powered by these engines is lengthy.

Properly maintained, they have a reputation for easily living their predicted lifespan, and then some.
 
There are two versions of the Lycoming 360: the parallel valve version and the angle valve version. The parallel valve version is often considered to be more reliable than the angle valve.
 
To expand on this - accident data has pretty much gathered the opinion that:

As long as you keep gas flowing to most all aircraft engines - they simply run.

Most general aviation aircraft engines are built with 1950s technology. This is intentional. There's a lack of computers, sensors, and other things to make the engine stop. Unlike cars, a "limp home mode" because some sensor is ****ed-off, wouldn't work well.

"Stuff happens" - is a VAST minority of the engine incidents. Overestimating your fuel, on the other hand, seems to be the major problem with engine stoppage.

May I presume this person is inviting you for a ride in his plane?
 
Carl Hammie said:
Hello, I have a buddy who owns an airplane with a 360 cubic inch Lycoming. I have never been in a small plane and I wonder how reliable these motors are?

Carl
Click to expand...

Very reliable compared to other weak points. I am little out of date, however historically the largest causes of small plane accidents is running out of fuel, of controlled flight into terrain (CFIT) which is often caused by visual restricted pilots flying into clouds.
So, just have your friend do a slow and careful pre-flight check; ask him/her to double check the fuel levels, and fly in good weather.

Tim
 
Lycomings tend to be more reliable than the pilots that operate them.
 
Carl Hammie said:
Hello, I have a buddy who owns an airplane with a 360 cubic inch Lycoming. I have never been in a small plane and I wonder how reliable these motors are?

Carl
Click to expand...
I don’t know if you should trust one? There are not that many out there and are still undergoing reliability testing.
I would wait until testing is complete if I were you.
 
To put in in car terms, the O-360 engines should go around 300,000+ miles without any work being done to the engine. Yeah, spark plugs will be replaced, or a starter or alternator, or other accessorial parts might need to be replaced in that time period but as far as the engine itself, you have to worry more about your buddy saying, "hey watch this," than the engine being the issue.
 
Gosh, if only someone collated data from accident reports.

Oh, wait. :)

The following is from my homebuilt aircraft accident database, covering Experimental Amateur-Built aircraft from 1998 through 2020. It's based on downloaded NTSB data. This data involves aircraft that are built and (largely) maintained by amateurs, so it might not be completely attributable to the great masses of production-type aircraft that use these engines.

In the analysis, I note whether power failure was involved in each accident, and whether mechanical problems with the engine were present. These would include both cases where the engine spontaneously failed, and cases where the maintainer made a mistake. Note that it does NOT include issues with fuel flow, either mechanical or wetware.

I "normalize" the aircraft and engine types in my spreadsheet, since the NTSB designation for either is pretty random. So the data catches "Lycoming O-320" as well as "Lycoming O320" and "Textron O 320". Not perfect, but should get most.

For each type of engine, I'll give the total number installed in aircraft during the subject period, as well as the percentage of those where mechanical failure of the engine was involved. "Mechanical Issues" includes accessories such as magnetos, PSRUs, and radiators.

This data is for fixed-wing aircraft only.

All Homebuilts: 4133 cases, 10.3% due to mechanical issues.

All Continental Engines: 426 cases, 9.2% due to mechanical issues

Continental A65: 47 cases, 6.4% due to mechanical issues

Continental O-200: 120 cases, 5.0% due to mechanical issues

All Lycoming engines: 1642 cases, 6.1% due to mechanical issues

Lycoming O-235: 109 cases, 6.4% due to mechanical issues

Lycoming O-320: 502 cases, 5.6% due to mechanical issues

Lycoming O-360: 276 cases, 5.4% due to mechanical issues

Subaru: 120 cases, 25% due to mechanical issues

VW: 197 cases, 22.3% due to mechanical failure

Rotax 912: 371 cases, 5.1% due to mechanical failure

So, for the OP, the Lycoming 0-360 engine in your friend's airplane is probably one of the more reliable ones...given the comments others have made about different versions of this engine.

Ron Wanttaja
 
Carl, you should understand that these motors are truly dirt simple, without any computer controls or high failure rate electronics. Furthermore, they have dual independent magneto ignitions, so one entire ignition system could fail and the engine would keep right on running. In fact, the plane can have a complete electrical failure and the engine will keep right on running. There's no timing belt or chain to fail; the camshaft is gear driven. The carburetor is as simple as can be, and has a manual mixture control. There are a pair of fuel pumps, one mechanical and driven by the engine and the other an electrical pump. There's even a second source for air to the carb.

The most common reason for an engine to stop running is fuel exhaustion. These older aircraft have notoriously inaccurate fuel gauges. Therefore, we judge fuel consumption by time, knowing how much fuel we have at the start by examining the tank directly. Nonetheless, the consumption rate is only an estimate and varies with throttle and mixture settings, so good pilots are extremely conservative about having enough fuel for the planned flight. (There's an old humorous truism that says the only time you can have too much fuel is when you're on fire.)

Besides inaccurate gauges, most aircraft have multiple fuel tanks that are selected manually by the pilot. One common way fuel exhaustion happens is that the pilot makes a mistake and selects the wrong tank. If he's thinking about what he's doing though, the mistake can be corrected easily. These engines are required to restart in the air in a matter of a few seconds when provided fuel.

When engines do have a mechanical failure, the reason can often be traced back to negligent maintenance.

The bottom line, then, is that the engines are designed to be very reliable, but can fail due to human error. So the real question you should be asking, if you're considering flying with your buddy, is not how reliable the engine is. Rather, ask how reliable he is.

Hope that helps a bit.
 
Carl Hammie said:
Hello, I have a buddy who owns an airplane with a 360 cubic inch Lycoming. I have never been in a small plane and I wonder how reliable these motors are?

Carl
Click to expand...
It'll run forever. And if it doesn't, you won't immediately hurtle from the sky like a meteor. Many single engine aircraft are adequate gliders, and can be force-landed in surprising short distances on dirt, grass, farm fields, deserts, highway medians, streets, warehouse roofs, treetops, beaches, etc. It might ruin the airplane but you'll probably go home with a great story. So, if it DOES quit, you're not necessarily doomed to mayhem and death.
 
Aircraft engines are more reliable than the guys driving them. How many hours does your friend have? I have a good friend who won't get into an airplane with any private pilot that has <500 hours. It's an arbitrary number but it's her rule.
 
Most of the airplanes built in the last 60 or 70 years are still flying. That says something about the reliability of their engines, and the durability of their airframes, if nothing else.
 
Dan Thomas said:
Most of the airplanes built in the last 60 or 70 years are still flying. That says something about the reliability of their engines, and the durability of their airframes, if nothing else.
Click to expand...

Are they flying past TBO and overhaul? I don’t think so ! So good maintenance is a key of realiability
 
Sd_flyer said:
Are they flying past TBO and overhaul? I don’t think so ! So good maintenance is a key of realiability
Click to expand...


Many of them fly past TBO. TBO is a somewhat arbitrary number, and lots of people only overhaul on condition.
 
Half Fast said:
Many of them fly past TBO. TBO is a somewhat arbitrary number, and lots of people only overhaul on condition.
Click to expand...

I believe it arbitrary only for part 91. Condition also depended on personal knowledge ! Some may wait until engine throw rod - other till lab shows some metal in oil . It not surprised though that cheapest airplane one can buy is typically with engine at or past TBO.
 
Sd_flyer said:
Are they flying past TBO and overhaul? I don’t think so ! So good maintenance is a key of realiability
Click to expand...
Considering Lycomings have a 12 year calendar time TBO, I’d say most of the private fleet is beyond tbo one way or another.
 
Sd_flyer said:
Are they flying past TBO and overhaul? I don’t think so ! So good maintenance is a key of realiability
Click to expand...
The point I was trying to make: If the engines were unreliable, there would be no old airplanes. They'd have crashed long ago. Even if rebuilt, they'd be likely to crash again. Even if they were well within TBO. Today's engines are a long ways from the engines of the 1920s, where occasional failure was expected.

We have laws that are designed to force proper maintenance. But there are a few that seem to think preventive maintenance is too expensive. Some others seem ignorant of the maintenance needs of things like magnetos and vacuum pumps and alternators, and run them to failure. People run the alternators in their cars to failure, too.
 
Sd_flyer said:
I believe it arbitrary only for part 91. Condition also depended on personal knowledge ! Some may wait until engine throw rod - other till lab shows some metal in oil . It not surprised though that cheapest airplane one can buy is typically with engine at or past TBO.
Click to expand...


The number itself is arbitrary. For part 91 it's not a requirement. For non-91 flying, it's required to adhere to the arbitrary number.

Oil analysis, borescoping, tracking oil consumption, etc., etc., can give decent insight into when an engine is on its last legs.
 
I would not have any qualms about flying behind one. Give it a shot, might spark a new interest!
 
Thank you everyone, my buddie offered a ride in his airplane but I was unsure about accepting. makes me feel better reading some of your knowledge. let me ask one other question as I’m quite ignorant to this all. If these engines are so reliable as some speak of, why are they not used in passenger jets? my impression is that commercial jets use jet engines for their reliability, so why are the Lycoming not used? I presume they also don’t provide enough lift to power a jet?

Carl
 
Carl Hammie said:
If these engines are so reliable as some speak of, why are they not used in passenger jets? my impression is that commercial jets use jet engines for their reliability, so why are the Lycoming not used? I presume they also don’t provide enough lift to power a jet?

Carl
Click to expand...
Change "lift" to "thrust" and yes, this would be correct.
 
Half Fast said:
The number itself is arbitrary. For part 91 it's not a requirement. For non-91 flying, it's required to adhere to the arbitrary number.

Oil analysis, borescoping, tracking oil consumption, etc., etc., can give decent insight into when an engine is on its last legs.
Click to expand...

I own 172P ‘84. I also instructed in nearly every 172 model from B to S) . I have overhauled my O360 twice already. I haven’t seen much going pass TBO. I have a feeling for the money I have spent for both overhauls I could have just bought new engine ! Lol

I’ve seen tons of neglected O360 that been destroyed before TBO. Those “lucky” O360 beaten up in flight school that surpassed TBO often on the last leg - with low compression, barely matching POH figures…Operator unlikely to do anything until someone have real trouble bringing airplane home.

So my take on prolonging engine life is careful handling and superb maintenance. If aircraft is used for training or club we can forget about “careful” right away :) Maintenance is greatly depends on mechanic. Unless of corse owner is A&P himself/herself
 
Carl Hammie said:
Hello, I have a buddy who owns an airplane with a 360 cubic inch Lycoming. I have never been in a small plane and I wonder how reliable these motors are?

Carl
Click to expand...

Carl,
This is your chance, maybe your last chance, to run screaming from the airplane and never look back.
Or you can hop in and have fun.
 
Just don’t let the Lycoming set very long without running. The cam is high so the oil drips off after a week or two. Camguard helps, but is not the end all solution. If it sets a really long time, one little corrosion spot will start tearing out one tiny piece at a time every time the cam lobe wipes over it. This is like a pothole that gets larger a tiny piece at a time. The lifters are mushroom shaped which means that the case must be split to change them.

The point is, don’t buy a Lycomingbthat has set for a long period of time. BTDT.
 
Carl Hammie said:
let me ask one other question as I’m quite ignorant to this all. If these engines are so reliable as some speak of, why are they not used in passenger jets? my impression is that commercial jets use jet engines for their reliability, so why are the Lycoming not used? I presume they also don’t provide enough lift to power a jet?
Click to expand...

The most powerful Lycoming engine is around 400 horsepower, and it's a rare engine. Most common big Lycs are 300 or so HP. Some airliner engines produce more than 100,000 HP, they last a very long time, they cost many millions, and they produce far more power per pound of engine weight than a Lycoming.
 
Dan Thomas said:
The most powerful Lycoming engine is around 400 horsepower, and it's a rare engine. Most common big Lycs are 300 or so HP. Some airliner engines produce more than 100,000 HP, they last a very long time, they cost many millions, and they produce far more power per pound of engine weight than a Lycoming.
Click to expand...

Not to mention the lack of oxygen at FL300 and above make for running an O360, well, near impossible.
 
Sd_flyer said:
I have overhauled my O360 twice already. I haven’t seen much going pass TBO.
Click to expand...
What was the reason for overhauling twice? Or even once for that matter?
 
Half Fast said:
Carl, you should understand that these motors are truly dirt simple, without any computer controls or high failure rate electronics. Furthermore, they have dual independent magneto ignitions, so one entire ignition system could fail and the engine would keep right on running. In fact, the plane can have a complete electrical failure and the engine will keep right on running. There's no timing belt or chain to fail; the camshaft is gear driven. The carburetor is as simple as can be, and has a manual mixture control. There are a pair of fuel pumps, one mechanical and driven by the engine and the other an electrical pump. There's even a second source for air to the carb.

The most common reason for an engine to stop running is fuel exhaustion. These older aircraft have notoriously inaccurate fuel gauges. Therefore, we judge fuel consumption by time, knowing how much fuel we have at the start by examining the tank directly. Nonetheless, the consumption rate is only an estimate and varies with throttle and mixture settings, so good pilots are extremely conservative about having enough fuel for the planned flight. (There's an old humorous truism that says the only time you can have too much fuel is when you're on fire.)

Besides inaccurate gauges, most aircraft have multiple fuel tanks that are selected manually by the pilot. One common way fuel exhaustion happens is that the pilot makes a mistake and selects the wrong tank. If he's thinking about what he's doing though, the mistake can be corrected easily. These engines are required to restart in the air in a matter of a few seconds when provided fuel.

When engines do have a mechanical failure, the reason can often be traced back to negligent maintenance.

The bottom line, then, is that the engines are designed to be very reliable, but can fail due to human error. So the real question you should be asking, if you're considering flying with your buddy, is not how reliable the engine is. Rather, ask how reliable he is.

Hope that helps a bit.
Click to expand...


Hmm, electronics are least likely to fail especially compared to mechanical contraptions - it is actually very simple - no moving parts, least likely to fail.
By your sort of logic, modern car engines being full of electronics, should not be able to even compete in terms of reliability with older carbureted versions - just the opposite is true.

I think the simple reason there is not much innovation in this market is because there is hardly any money in the GA market to begin with so you are stuck with 70 year old designs , like it or not.
 
I’ve had electronics fail in several cars now, though they go to a “limp-home” mode when they fail. My MINI was especially bad about it. Most often it’s a sensor that fails.
 
when electronics fail, there’s rarely a work around (get known good part), it’s amazing (scary actually) what can be MacGyvered on the mechanical stuff.
 
Warmi said:
Hmm, electronics are least likely to fail especially compared to mechanical contraptions - it is actually very simple - no moving parts, least likely to fail.
By your sort of logic, modern car engines being full of electronics, should not be able to even compete in terms of reliability with older carbureted versions - just the opposite is true.

I think the simple reason there is not much innovation in this market is because there is hardly any money in the GA market to begin with so you are stuck with 70 year old designs , like it or not.
Click to expand...
Electronics are dependent on electrical supply. If that fails, the electronics fail. And in small aircraft, alternators and charging systems are the most troublesome systems in the whole airplane. If we had EI and EFI in our airplanes, we'd need two alternators and two batteries, two totally independent systems feeding the engine electronics via diodes. You'd never get certification without it. I was told, in Power Mechanics class in high school some 53 years ago, that electrical problems were 90% of engine problems. I have found that to be true ever since.

Which is why we still have magnetos on our engines even though cars abandoned them maybe 90 years ago. They are self-contained and will continue to fire even if the airplane's electrics fail. But they are also prone to failure if they're not maintained, which is why we have two of them. We have only one carburetor because it has little tendency to fail unless we try to feed it water, or if we are ignorant about carb ice and its management.

Lycoming has the iE2 engine. Been available for years already. Electronic ignition, electronic fuel injection. But it's not cheap, and aircraft owners being cheap, they don't sell many. A European airframe manufacturer is using them.

upload_2022-7-28_21-8-20.png

I see two alternators on that engine.

https://www.lycoming.com/engines/ie2

From its TCDS:

upload_2022-7-28_21-17-59.png
 
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