Why are airplane engine TBO hours so low?

Dan Thomas said:
Well, for a "failed" engine they're still marketing it. https://www.smaengines.com/our-product/sr305-230er

Wiki's page on it was last edited on February 26, 2020. It ain't dead yet. https://en.wikipedia.org/wiki/SMA_SR305-230
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That wiki page also says that it WILL go into 182 in 2013. Given that this its only application and Cessna chose not to use it, I’d say it’s a failure

Astro that is going to DA50 seems like a better choice. I suspect cirrus will probably wait to seee how diamond is doing with it first.
 
genna said:
That wiki page also says that it WILL go into 182 in 2013. Given that this its only application and Cessna chose not to use it, I’d say it’s a failure

Astro that is going to DA50 seems like a better choice. I suspect cirrus will probably wait to seee how diamond is doing with it first.
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The SMA is STC'd for the 182Q and there and numerous examples of those flying. SMA sold or licensed the technology to Continental, and the Continental version was the one Cessna was going to use in the JT182. Cessna cancelled or paused that project since 182 sales, along with the 172 aNnd206, were too low to justify it.

Austro was the result of the Thielert failure and there are examples flying. The two engines (SMA and Austro) are completely different philosophies. The Austro is a converted Mercedes engine with a PSRU. The SMA is a clean-sheet design, direct-drive. Both are plenty expensive compared to a Lycoming or Continental, and both must be replaced, not overhauled, at TBO. There are few service centers for them, and even there the amount of repair permitted is limited.
 
Dan Thomas said:
The SMA is STC'd for the 182Q and there and numerous examples of those flying. SMA sold or licensed the technology to Continental, and the Continental version was the one Cessna was going to use in the JT182. Cessna cancelled or paused that project since 182 sales, along with the 172 aNnd206, were too low to justify it.

Austro was the result of the Thielert failure and there are examples flying. The two engines (SMA and Austro) are completely different philosophies. The Austro is a converted Mercedes engine with a PSRU. The SMA is a clean-sheet design, direct-drive. Both are plenty expensive compared to a Lycoming or Continental, and both must be replaced, not overhauled, at TBO. There are few service centers for them, and even there the amount of repair permitted is limited.
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Yes. All true. STC for any diesel is generally non-starter(except for where avgas not available). As you pointed out it makes no financial sense. But once they go into new production planes it’s a whole other story. Diamond is making it work for them but the big guerrilla is still sr22. 182 is pretty irrelevant now. Will they do it? I don’t know. Maybe they can’t make it work in that airframe. Maybe they feel it’s not worth it. But my personal opinion it’s the only way forward and the only way to get a new engine design philosophy into piston ga
 
Don’t forget that sr22T may have 2000 tbo, but they usually eat a few cylinders in that period.
 
Side note. If I were buying new 200mph plane, I wouldn’t really care much about tbo. 2000h is 350k miles and something like 20-30 years for me. There is something to be said about resale values, but that’s a relatively small penalty on a 1MM new plane. What I’d care more about is operational cost, reliability(this is a big question with anything new), and ease of use.
 
Bob Noel said:
Idle thought: Why complain about a 2000 hour TBO for an engine in the airplane that flies less than 30 hours per month? How many of the small GA engines reach calendar TBO before operating hour TBO?
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Probably the majority of them.

What I read, many of the trainers well exceed 2,000 hrs. One article had a retraining fleet that topped them at 2,000 hrs then overhauled at 4,000 hrs. Regularly, not flukes.

Those that fly 50 hrs a year don't seem to make TBO. Fly them 300 hrs a year or more and exceeding TBO is more common.



Wayne
 
wayne said:
Probably the majority of them.

What I read, many of the trainers well exceed 2,000 hrs. One article had a retraining fleet that topped them at 2,000 hrs then overhauled at 4,000 hrs. Regularly, not flukes.

Those that fly 50 hrs a year don't seem to make TBO. Fly them 300 hrs a year or more and exceeding TBO is more common.



Wayne
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An FBO/flight school owner who I knew decided out of caution to overhaul the O-360 in his 172 at 3,000 hours even though compressions were great and oil consumption was low. He found everything was still practically within new tolerances.

The plane normally flew seven days a week, two or three flights a day, and rarely sat for more than a couple days if the weather stunk.
 
Rockymountain said:
If Car engines did a good job in planes, we would see car engines in planes. They don’t work, they don’t hold up, they can’t handle the stresses. Perhaps the closest is the Austro diesels, heavily modified, but they are heavy, while still being puny.
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There have been a few engines successfuly converted, but mostly one-offs where the builder got everything almost all right. Even then, some of them have required endless tinkering to try to work out bugs. The engine itself, if it's a robust engine and as long as it has adequate cooling (which can be difficult without causing a whole lot of extra drag) will operate at high power levels for extended periods, though 2000 hours might be a fantasy.

There have been countless attempts that cost big bucks and years of effort, only to be pulled off the airplane in frustration and replaced with an aircraft engine. Same old stuff: If you want to build, build. If you want to fly, buy.
 
Dan Thomas said:
You're adding a LOT of weight, and weight is the enemy, to say nothing of a lot more failure points. Works good in vehicles that don't fly.

Words like could and might and likely just don't get anything done. They're just signs of wishful thinking, not based on any real facts and numbers or knowledge of the issues. Real facts and numbers gave us the engines and airplanes we have now. Real facts and numbers are currently seriously hampering useful and practical electric flight.
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Back-of-the-napkin check:

Continental IO-520 weight: 184kg
Rotax 300 HP 1630 86kg, Tesla 10kWh - 62kg, Tesla 362 HP electric motor: 31kg = 179kg

The math checks out - just needs a bit of engineering. Unlike with pure electric, which isn't supported by current science.

Note, this isn't the general: "Hybrid is more efficient" argument. It's not and won't ever be. There is no regen to be had in the air that can make it more efficient. This is a "hybrid-electric can be cheaper and equally as safe as avgas piston" argument.

You may or may not lose range due to the gasoline-electric conversion factor. (There's about a 15% cost of conversion, but OTOH you're comparing 2020 fuel injected engines against 1940 carburetor engines). But even if the conversion loss is 15%, petrol is more than 15% cheaper than avgas.
 
deonb said:
Back-of-the-napkin check:

Continental IO-520 weight: 184kg
Rotax 300 HP 1630 86kg, Tesla 10kWh - 62kg, Tesla 362 HP electric motor: 31kg = 179kg

The math checks out - just needs a bit of engineering. Unlike with pure electric, which isn't supported by current science.

Note, this isn't the general: "Hybrid is more efficient" argument. It's not and won't ever be. There is no regen to be had in the air that can make it more efficient. This is a "hybrid-electric can be cheaper and equally as safe as avgas piston" argument.

You may or may not lose range due to the gasoline-electric conversion factor. (There's about a 15% cost of conversion, but OTOH you're comparing 2020 fuel injected engines against 1940 carburetor engines). But even if the conversion loss is 15%, petrol is more than 15% cheaper than avgas.
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Petrol (Mogas, as we know it) might be cheaper than avgas, and there are many aircraft engines that can be legally run on it. You also have to figure in the battery cost and life and add that to the operating costs.

You'd need a really good alternator/generator to meet any 15% conversion loss limits. Most lose a lot more than that. And then there's the losses in the electric motor due to heat.

About the only advantage I would see with hybrid is the use of an automotive engine in an aircraft without the problems of torsional vibration. No prop speed reduction, no gears to fail. With and electric motor there are no big power pulses to deal with so the gears are more likely to take the loads safely. You'd still need to deal with the connection between the engine and generator; a heavy rotor will cause TV in any drive coupling or gearing.
 
genna said:
Wasn’t SMA engine a failure?
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Basically, yes. The latest work on it is by Soloy, who were trying to get it STCed for the C182 but still had issues primarily around the cooling. Soloy was sold recently and the guy who took everything over has pretty much gone silent, so it seems dead for now.

Oh, and before Soloy were sold they were quoting between $160k and $240k for an engine package...

The existing Gen 1 engines in various 182s are... not the greatest.
 
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Capt. Geoffrey Thorpe said:
I assume the reason they went defunct was that they were skimping on maintenance on both the engine and airframe. Not the first operation to have that problem - I know of a former school that lost 100% of their aircraft to mechanical issues with their Lycomings.
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Some years ago our Club purchased two Contenental powered Diamonds. We put them on the ramp at exactly the same price as the 172s. They averaged 1/2 the hours per month as our 172 fleet average (~900 hours per 172 per year). They just weren't as popular with either the students or club renters for some reason.

Then one day, in the "heat" of a northern Rockies summer the rear window on one plane cracked. That window is structural. Took Diamond months to come up with an approved procedure to replace that window and then another couple months to supply the replacement component and material to make the repair.

As for the Rotax, one of the common problems we've seen around our airport is operators running them on 100LL (instead of mogas, which is not available at our airport) and not adjusting the oil change interval frequency per Rotax. One flight school here that made that mistake was told by Rotax that 5 of the 6 pre-maturely worn engines on their three Technam P2006T trainers were not rebuildable.
 
Isnt it better to compare aviation engines to motorcycle engines? My truck rarely turns more than 1700rpm compared to my Harley which likes to be above 2500rpm. I know if I get 100,000 miles on the Harley engine without maintenance then I was a good owner(or lucky). Even Honda motorcycle engines seem to become problematic around the 100k area. So the motorcycle engine seems to be more like a plane engine than a car engine.
 
charheep said:
Isnt it better to compare aviation engines to motorcycle engines? My truck rarely turns more than 1700rpm compared to my Harley which likes to be above 2500rpm. I know if I get 100,000 miles on the Harley engine without maintenance then I was a good owner(or lucky). Even Honda motorcycle engines seem to become problematic around the 100k area. So the motorcycle engine seems to be more like a plane engine than a car engine.
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No, because like auto engines, the engine is normally loafing along for most of its life. It is easy to make an engine last for 100K miles if it is running at 20-30% of its maximum power most the time. Aviation engines run at 60-70% power most of the time. The "best" comparison is a marine engine, since they run under heavier loads than aviation and often have similar usage patterns (typically sporadic weekend use, 50-100hrs/year).
 
Sure, if you ignore all the automotive failures they are bulletproof...

Timing chains, timing tensioners fail, valves break, rounded cam lobes, busted connecting rods, they are out there. One of my favorites, some those hemis had the valve seats falling out of the heads.

My Dad's C50 Chevy just broke a rod, this truck has had THREE brand new crate GM 350s in it since it was new. The grain truck has a whopping 80k miles on it. My grandpa bought the truck brand new.
 
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genna said:
but they usually eat a few cylinders in that period
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I was part of a few private Cirrus clubs plus a dry lease arrangements. The engines in these planes all needed work prematurely. One needed work just 800 hrs in. This was especially true in the club we had with eight members.. but I think part of this, as much as I hate our old engines, is because of poor engine management. It got to the point where the club head would do public shaming emails of flights that were poorly leaned. Somehow I managed to keep that engine always under 380 and usually in the 350-360 range.. some people though would cruise for hours with thing in the 400-420 range due to poor leaning and management technique. (Lots of people have no idea whot LOP is and incorrectly think that lean=hot). Which kind of goes back to the earlier point about FADEC. Even if the engine itself "must" be the way it is (large displacement, low RPM, etc.) we could at least utilize FADEC to mitigate operator error. Most pilots aren't engineers, especially people buying Cirrus.. they're used to a catered world. Give them a throttle and let a computer (or 3 or four of them for redundancy) figure out what the pilot is asking for and provide that.

genna said:
If I were buying new 200mph plane, I wouldn’t really care much about tbo
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No, but you will care when you can't fly your plane 30% of the time because there consistently seems to be some issue with the engine. Your million dollar toy is in the shop, AGAIN, and you have to fly commercial to Vegas like some kind of proletariat.
 
WDD said:
Rotax engines (912) are built using new technology. It has a TBO of 1500 hours, similar to the death trap Continentals mentioned above. This tells me it is more of the demand placed on the engine for the weight and size than simply bad engineering and bad construction.
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Rotax 912 TBO has been 2,000 hrs. since 2009.
 
Tantalum said:
I was part of a few private Cirrus clubs plus a dry lease arrangements. The engines in these planes all needed work prematurely. One needed work just 800 hrs in. This was especially true in the club we had with eight members.. but I think part of this, as much as I hate our old engines, is because of poor engine management. It got to the point where the club head would do public shaming emails of flights that were poorly leaned. Somehow I managed to keep that engine always under 380 and usually in the 350-360 range.. some people though would cruise for hours with thing in the 400-420 range due to poor leaning and management technique. (Lots of people have no idea whot LOP is and incorrectly think that lean=hot). Which kind of goes back to the earlier point about FADEC. Even if the engine itself "must" be the way it is (large displacement, low RPM, etc.) we could at least utilize FADEC to mitigate operator error. Most pilots aren't engineers, especially people buying Cirrus.. they're used to a catered world. Give them a throttle and let a computer (or 3 or four of them for redundancy) figure out what the pilot is asking for and provide that.


No, but you will care when you can't fly your plane 30% of the time because there consistently seems to be some issue with the engine. Your million dollar toy is in the shop, AGAIN, and you have to fly commercial to Vegas like some kind of proletariat.
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Just gonna point out the irony with you asking for fadec to keep things simpler...yet complain about the 172 fuel system being too simple and not having to manage fuel.
 
Racerx said:
172 fuel system being too simple
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I think my critique of the 172 was 13 fuel sumps and no way (on several models) to sump the gascolator without polluting or actually testing the sample. I never spoke ill of the PA28's system
 
Tantalum said:
I think my critique of the 172 was 13 fuel sumps and no way (on several models) to sump the gascolator without polluting or actually testing the sample. I never spoke ill of the PA28's system
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I never had any trouble getting the sample cup under the 172's fuel strainer while pulling the drain cable. On a 185 or 206 it's a much bigger hassle. There are STC'd fuel strainers that get away from the Cessna type, parts for which are horribly expensive, and the new ones are much easier to service, too.They use the simple push-to-drain Curtis valve, same idea as the wing sump drains. But then you have to bend down, don't you? Something else to complain about.

SA3-00-B_2_sml.jpg


https://www.stevesaircraft.com/gascolator.php

And as I've pointed out before, those numerous wing sump drains are due to the stiffeners in the bottom of the tank bay. The 172R/S have integral tanks, no separate tank inside the wing. Stiffeners can trap water. Anyone that has to complain about the extra 12 seconds per wing to sump those things has life way too easy. The older 182/R182, 185 and 180 had bladders notorious for wrinkling, and the wrinkles would trap water, accumulating it until the airplane encountered some turbulence, whereupon the water would all migrate to the outlet and overwhelm the fuel strainer. Engine quits. There's an AD on those that requires you to lower the tail and rock the wings up and down 12 inches a whole bunch of times to dislodge that water and get it to the sump drain, and have the mechanic open the tank and check the wrinkles every annual and test to see how much water thay trap, or spend a bunch of money on a raised fuel-cap mod to get away from the leaking flush-cap problems. Now there's something to complain about.
 
Tantalum said:
I think my critique of the 172 was 13 fuel sumps and no way (on several models) to sump the gascolator without polluting or actually testing the sample. I never spoke ill of the PA28's system
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"(13) BOTH fuel..
(a) this teaches very poor fuel management and discipline, resulting in threads where people ask "why it is so hard to manage fuel?""
 
Racerx said:
"(13) BOTH fuel..
(a) this teaches very poor fuel management and discipline, resulting in threads where people ask "why it is so hard to manage fuel?""
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fine. But the reason behind that is the typical plane people will be stepping up to ultimately are far more complex and challenging than what a 172 gives them. It's like learning to drive stick on an old Tacoma then buying a brand new sports car and not understanding why you can't do a hill start. If all planes were fadec with easy fuel systems to manage I might not have this critique of the Cessna, as I find it leaves one ill prepared for the planes they'll some day fly
 
Tantalum said:
fine. But the reason behind that is the typical plane people will be stepping up to ultimately are far more complex and challenging than what a 172 gives them. It's like learning to drive stick on an old Tacoma then buying a brand new sports car and not understanding why you can't do a hill start. If all planes were fadec with easy fuel systems to manage I might not have this critique of the Cessna, as I find it leaves one ill prepared for the planes they'll some day fly
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I get what you were saying, just couldn't resist. I was contemplating buying a Cherokee 160 or 180 to train in rather than my dad's Cherokee Six. I'm not a fan of renting. He was fine with me putting hours on it and I'm fine with the extra 30 bucks an hour in fuel. I was concerned with having to manage the constant speed prop but it hasn't been a big deal.
 
Tantalum said:
If all planes were fadec with easy fuel systems to manage I might not have this critique of the Cessna, as I find it leaves one ill prepared for the planes they'll some day fly
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And then nobody could afford the training.
 
Racerx said:
I get what you were saying, just couldn't resist. I was contemplating buying a Cherokee 160 or 180 to train in rather than my dad's Cherokee Six. I'm not a fan of renting. He was fine with me putting hours on it and I'm fine with the extra 30 bucks an hour in fuel. I was concerned with having to manage the constant speed prop but it hasn't been a big deal.
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That's a fantastic deal! The Cherokee Six is a veritable beast. Big comfortable airplane. I don't mind CS, I almost feel like you have better power management control.. set the RPM and just manage MP for power.
 
Dan Thomas said:
And then nobody could afford the training.
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Well that part's a catch-22, but I suppose most of flying is with regards to cost, volume, tech. etc.

Just because it's the best we got (for reasons XYX) doesn't mean we have to be happy with it. But this seems to be a trend in aviation, and I wonder if that's more indicative of the type of persona that tends to become pilots. When "glass" first started becoming a thing there was a big reluctance to it.. "real pilots" are fine with steam. Glass is less safe, it will make you complacent, yada yada yada. When my school in Boston got their first PA-28-161 with a 430 I was basically told not to use it, that it will make me less situationally aware and to use the maps and steam VOR needles for navigation. But ultimately just about everyone today is putting something glass in their plane, whether it's an Aspen, G5.. heck even a 650 (imho) is a form of glass. Even many of our club beater rentals have dual G5s, now, etc.

There seems to be a general resistance to change in this field. At least we have started seeing electronic ignitions in planes (in place of one mag) and there's very slow change. FWIW the planes with the one elec mag consistently start much more easily and the "mag drop" on the electric side is minimal, like 25, at least in the planes I've flown with it
 
DenverDave said:
Modern sports cars are way easier to hill start than an old Tacoma.
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..through the advancement of tech we've made something easier? That same tech that has made the sports car easier to drive is not there in the GA fleet. The point was learning to drive on something with a large, dumpy, and forgiving clutch really doesn't prepare someone to drive something with a tight and short clutch. I think many of our accidents, hard landings, bent metal, are the result of someone jumping from a 172 into a Mooney, Bonanza, Cirrus, etc. withouth the proper transition. Just about anyone can drive a Tacoma, pathfinder, what have you. Put someone in a late 90s BMW, Celica, Miata, whatever and they'll be stalling that thing left and right

Piper also designed the PA-28 series to be rugged and economical and has a good step up line as well. Piper still builds some variation of most of their fleet, Cessna doesn't really. They exist solely for the flight schools. Piper also has a diesel line up for the European market..

It's okay, if the 172/182 is your cup of tea, and the market has obviously spoken that people are happy tinkering with mixture controls and tolerating all the maintenance that babying these elderly engines requires. That's fine. 172/182 has sold in huge numbers so there was obviously a market for it. Their sales have since dried up (except for flight schools) but that's more on Textron. I prefer something that's tighter, faster, and funner to fly. I simple don't have the need to put four people and gas into a 130 knot 14gph plane and fly between grass strips. If I did, I would tolerate all the issues I have with the 172/182
 
Tantalum said:
That's a fantastic deal! The Cherokee Six is a veritable beast. Big comfortable airplane. I don't mind CS, I almost feel like you have better power management control.. set the RPM and just manage MP for power.
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Took a bit to get used to. Was worried it was going to be too much to manage but that hump went away pretty quickly. Shoulder room is so under rated. Sure it's not fast. But it will haul pretty much anything.
 
DenverDave said:
It goes the other way too, remember that idiot who learned to fly in a Cirrus and loaded up a rental 172 and took off with full flaps? IIRC he had no 172 time and still took passengers. RIP. You have to know the plane you're flying.

Every manufacturer knows of the gaping hole in demand for new airplanes, the cheapskates won't pay 200k for a plane and the big spenders have no problem spending 500k-1m+ on a plane. Cirrus shipped 53 SR20s, 131 SR22s and 200 SR22Ts last year. It's really hard to roll out affordable innovation when a home run would be selling 500 150k planes a year.
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I think this is why you see an average of 57 new rV-10's being completed every year. A new plane isn't 200k. Closer to 300k. For half the price you get more plane and less restriction. It's just time. As time goes on and our GA fleet continues to succumb to attrition, I think the EAB market becomes more attractive. Unless they do something significant with light sport restrictions.
 
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Tantalum said:
Glass is less safe, it will make you complacent, yada yada yada. When my school in Boston got their first PA-28-161 with a 430 I was basically told not to use it, that it will make me less situationally aware and to use the maps and steam VOR needles for navigation. But ultimately just about everyone today is putting something glass in their plane, whether it's an Aspen, G5.. heck even a 650 (imho) is a form of glass. Even many of our club beater rentals have dual G5s, now, etc.
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Glas does make you complacent. I saw it in the flight school. If we simulated a nav failure, the pilot had no idea where he was. He wasn't thinking. This can be fatal in an airplane, mot so much in a car.

Thinking seems to have become a lot harder with all the gadgets. If we ever have a major solar flare that takes out some of the GPS constellation we'll have a lot of pilots too scared to leave the circuit.
 
But that's a fault of instruction then. If you're tracking a VOR and it fails or dies then (a) you might not know the thing has died until you're way off course and (b) someone may be just as caught off guard "where am I-deer in headlights" if they're just mindlessly droning along following the CDI. VFR you should be able to find yourself easily. IFR.. you're just as screwed without your nav as you are without the magenta line. Time to grab the compass and the stopwatch and bust out the navlog!!
 
David Megginson said:
Diesel retrofits have been a marketing failure, because no one who can do basic arithmetic wants to pay $50K to retrofit a diesel into a $40K used Cessna or Piper to save $500/year in gas.
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Forgot to add they weigh more and produce less horsepower.
 
Tantalum said:
But that's a fault of instruction then. If you're tracking a VOR and it fails or dies then (a) you might not know the thing has died until you're way off course and (b) someone may be just as caught off guard "where am I-deer in headlights" if they're just mindlessly droning along following the CDI. VFR you should be able to find yourself easily. IFR.. you're just as screwed without your nav as you are without the magenta line. Time to grab the compass and the stopwatch and bust out the navlog!!
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The VOR has the to/from flag that disappears when the transmitter fails. Or an OFF flag. If one is navigating with it, checking that is SOP. If you're on an IFR approach, you should have the identifier signal an low audio, too. IFR training.

Situational awareness means that you should know roughly where you are, on the map, at any given time. You should have an ETA for various checkpoints whether VFR or IFR.

Anything else means you're just a passenger if the radios die.
 
Racerx said:
Forgot to add they weigh more and produce less horsepower.
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SMA's engine, supposedly 230 HP is actually 227, but it pulls a 182 well because it does it at 2200 RPM. At lower propeller speeds there is less drag on the prop, so more power goes into thrust instead of drag.
 
There will be new, more advanced and reliable engines, perhaps not in everyone's lifetime, but they will. I spoke with Wankel Supertec and they indicated their diesel/kerosine powered engine will be available around 2022. They are also working on H2 powered Wankel engine, which is a next breakthrough in the engine market, although timeline for H2 engine is not that clear.
 
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