Move over ROTAX...

[skippydiesel]

11 minutes ago, turboplanner said:

My definition for TBO is with scheduled maintenance and perhaps one or two minor unscheduled events with an obvious cause which, when corrected will take it over the line.

 

That's the equivalent of time to an in-frame rebuild in a truck.

That's your definition but you asked for manufactures statistics - what of their definition?

 

My definition of meets TBO,  is with ONLY routine servicing  and relates to the engine model not individual good/bad luck.

Anything more than servicing, is an intervention, the level of the intervention is the key.

Replacing a seal might be considered minor, a valve/seat not so, neither is a cylinder head or pistons, etc. The later, costly in parts and labour.

If costly work is the norm (ie routine) then the engine model is failing to make TBO and the manufacturer's claims are bogus.

There will always be the individual claim - my engine made TBO & then some, without costly intervention. This does not constitute proof that the engine model makes the manufacturer's claimed TBO. Just as the unfortunate whose engine haemorrhages at 500 hrs, does not condemn the whole engine model.

[turboplanner]

Just now, skippydiesel said:

That's your definition but you asked for manufactures statistics - what of their definition?

 

My definition of meets TBO,  is with ONLY routine servicing  and relates to the engine model not individual good/bad luck.

Anything more than servicing, is an intervention, the level of the intervention is the key.

Replacing a seal might be considered minor, a valve/seat not so, neither is a cylinder head or pistons, etc. The later, costly in parts and labour.

If costly work is the norm (ie routine) then the engine model is failing to make TBO and the manufacturer's claims are bogus.

There will always be the individual claim - my engine made TBO & then some, without costly intervention. This does not constitute proof that the engine model makes the manufacturer's claimed TBO. Just as the unfortunate whose engine haemorrhages at 500 hrs, does not condemn the whole engine model.

My definition is the manufacturers definition. Yours is the purist. In practice you can receive say a month’s supply of a component and the in a month’s time get failure reports from customer. That doesn’t make it a bad engine; you just replace those components under warranty during scheduled services and the engine will go to its TBO point.

 

if you pull this data you’ll know which product is best rather than listening to biased gossip and only finding out they were wrong when it’s your money down the drain.

[skippydiesel]

2 minutes ago, turboplanner said:

My definition is the manufacturers definition. Yours is the purist. In practice you can receive say a month’s supply of a component and the in a month’s time get failure reports from customer. That doesn’t make it a bad engine; you just replace those components under warranty during scheduled services and the engine will go to its TBO point.

 

if you pull this data you’ll know which product is best rather than listening to biased gossip and only finding out they were wrong when it’s your money down the drain.

Yous is a marketing fabrication that will differ from manufacturer to manufacture & over time, as it suits the sales targets - it can not be used as a legitimate measure of reliability/quality.

 

So, say Rotax make a claim for their 912ULS of 2000 hrs TBO and the vast majority of these engines actually make TBO (++) with just routine servicing.

Say Lycoming make the same claim for their IO-233 and most require pistons/valve work/push rod (I am making this up to make the point) say at 1000 hrs - can you legitimately claim that this is just a minor intervention /low cost and the engine will make its 2000 hr TBO ?

[turboplanner]

12 minutes ago, skippydiesel said:

Yous is a marketing fabrication that will differ from manufacturer to manufacture & over time, as it suits the sales targets - it can not be used as a legitimate measure of reliability/quality.

 

So, say Rotax make a claim for their 912ULS of 2000 hrs TBO and the vast majority of these engines actually make TBO (++) with just routine servicing.

Say Lycoming make the same claim for their IO-233 and most require pistons/valve work/push rod (I am making this up to make the point) say at 1000 hrs - can you legitimately claim that this is just a minor intervention /low cost and the engine will make its 2000 hr TBO ?

No. 
However minor is minor and temporary.

Yes, marketing and manufacturing cross over but the market leaders usually have the better engines over the long term.

 

 

 

 

 

 

 

 

[BurnieM]

So what are the numbers for the 912 ULS (on the market for 24 years) and the 912 IS (on the market for 11 years).

 

These are pretty reasonable time periods and would have thought we would all have a pretty good warm fuzzy feeling by now.

 

Edited December 4, 2023 by BurnieM

[skippydiesel]

I confess, as a Rotax 9 user/suporter that "all have a pretty good warm fuzzy feeling by now" BUT unfortunately this, in the absence of objective data, is just that, a warm fuzzy feeling.🙂

[LoonyBob]

Ahem. For a Certified engine, TBO refers to the core; "tops" are just an incidental.

 

The requirement is that any part or item of the engine should be able to run 2 inspection intervals with a flaw but no failure, that it be detected and remedied before failure. 100 hourlies, anyone? DIs?

 

Skip, any engine can be abused. Run a bit lean, expect to see valve troubles. Run a lot lean, kiss your pistons goodbye. Wrong sparkplug heat rating for the prevailing conditions? Run a dodgy batch of MOGAS in unusually hot conditions? Get in the habit of exceeding the 5-minute rating? Mice nibble a hole in some SCAT? https://www.aviationsafetymagazine.com/squawk_box/more-lycoming-woes/

 

The defining target for SRE GA is a probability of catastrophic or serious (involving fatality) accident of one per 1000,000 hours of operation for the whole aircraft. GA achieves about 1 in 810,000 last time I looked. Reacreational (worldwide) achieved ~ 1 in 435,000 over the same interval, if memory serves me

What kinds of engine failure produce a significant probability of fatality? Depends on how much IFR one flies in one's piston single; but Contacomings maintained IAW the manufacturer's schedule, by a LAME, achieve total loss of power during flight &/or engine fires at less that 1 per 1000,000 operating hours... but they have other failure modes. https://aviation.stackexchange.com/questions/21599/how-reliable-are-lycoming-and-continental-general-aviation-piston-engines

 

Lycoming alone have books full of SBs involving upgrades to eliminate failure modes, discovered after Certification.

Edited December 4, 2023 by LoonyBob

[LoonyBob]

30 minutes ago, skippydiesel said:

I confess, as a Rotax 9 user/suporter that "all have a pretty good warm fuzzy feeling by now" BUT unfortunately this, in the absence of objective data, is just that, a warm fuzzy feeling.🙂

Er, I though most 912s and all bigger 9xxs were certified against JAR 22 or better?

[LoonyBob]

To be fair, Continental and Franklin also have a good weight of SBs...

[turboplanner]

9 hours ago, turboplanner said:

No. 
However minor is minor and temporary.

Yes, marketing and manufacturing cross over but the market leaders usually have the better engines over the long term.

Skippy there's no point in just laughing at what I say.

I live and work in the industry that produces the most ICE motors.

You may well be able to tell me of a motor which made your definition of TBO, but that's no use if it was the only one out of 500.

We can't take into account whether an operator does the right thing when he uses it; we can't take into account whether the owner has it serviced with the correct products at the correct intervals etc., we just look at failures per 100 engines.

 

You are still welcome to get statistics on your benchmark of zero non-scheduled maintenance to TBO,

and you will probably find some.

 

You will get a bigger and better comparison at my benchmark of issues that didn't create downtime or cost.

 

To put it in perspective the picture shows where you start doing a four year analysis on this product. The engine in this one is good for 1.4 million km to in-frame rebuild. Usually it would be sold by this owner at about the three year mark. The buyer would use it for local work and get about five years out of it, then rebuild the engine etc.

 

You can see from this chart that the owner's focus will be on fitting air sheild kits, gearing to minimise fuel consumption etc. nut not spend a lot of time anguishing over that small R&M column which includes scheduled maintanance, and non-scheduled maintenance on everything, not just engines.

 

The chart is for one Application.

 

If you break your own Aircraft Chart down, it will look different, and if the R&M column dominates the rest, then you certainly will be focused on engines but its the ones that keep R&M at an unsustainable level that need to be eliminated from purchase decisions.

 

For that you need a big cross section of records to look at.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[facthunter]

Trucks Ain't planes. Planes make their engines as light as possible. That's a big difference. . A heavy motor for a plane won't sell. . A lot of them also sit for long periods unused. The beginning of every journey is full throttle for about 5 minutes. Each motor is considered to be delivering rated power till it's pulled. It's not "worn out" in the conventional sense. Very few aviation motors are diesels. Planes can't pull over and lift the cab up and fix things.. Most are air cooled.  TBO is not much more than a Guess in most cases. It used to have to be established in a proven way. That seems to have gone. Running motors "on condition" often causes a more expensive rebuild for a few hundred hours extra.

  I knew Bert Flood way back and he showed me more than the ordinary bloke gets to see regarding the 912 and probably the 80 HP will be their best engine . (that's my opinion and a few others also)  The carbs are crap for a plane and shouldn't be on the top of the motor. Nev

[skippydiesel]

8 hours ago, LoonyBob said:

Er, I though most 912s and all bigger 9xxs were certified against JAR 22 or better?

 I haven't really been involved in certified aircraft for about 15 years so got no idea - my intersted & I suggest, that of most small aircraft owners is how reliable (safe & minimal down time) is it and how much will it cost me to operate. 

 

As for your earlier comment - "Ahem. For a Certified engine, TBO refers to the core; "tops" are just an incidental." - The industry can come up with whatever convention it may wish (to justify a poor product) however I don't accept  that a routine (ie expected/scheduled) substantial rebuild (starting from the core) can be considered anything less than a partial/total recondition. If an engine model is subject to this level of pre TBO intervention it is not making the manufacturer's claimed TBO.

 

 

 

[facthunter]

The industry is concerned with safety.  Valves are a critical component in an aircraft engine. "To Justify a POOR product" is YOUR conclusion. There's an element of "inspection" involved as well. Even Rotax has a problem of possible seat damage with leaded fuel. IF you fly behind a Piston engine the more you are familiar with how it's going the less unpleasant surprises you will Have. Fit and Forget is not realistic  with planes.   Nev

[skippydiesel]

1 hour ago, facthunter said:

The industry is concerned with safety.  Valves are a critical component in an aircraft engine. "To Justify a POOR product" is YOUR conclusion. There's an element of "inspection" involved as well. Even Rotax has a problem of possible seat damage with leaded fuel. IF you fly behind a Piston engine the more you are familiar with how it's going the less unpleasant surprises you will Have. Fit and Forget is not realistic  with planes.   Nev

Nev, I did not make my opinion clear - its the TBO hour claim, that is to say if your engine model has say a 1000 hr claim and significant engine work is done at/after this time in service , then I would consider the TBO claim valid.

If on the other hand you have  the same engine model with a claimed 2000 hr TBO and the model has a fair reputation for needing work done at 1000 hrs, I would say the TBO is overstated/bogus.

 

This debate started around Turb's suggestion that TBO could be used as a comparative measure of engine service reliability (paraphrase) - I don't think it can due to the influence of the various engine manufacturers marketing department on the TBO times generated - way to much hope & a prayer generated by differing faiths 😄

[turboplanner]

32 minutes ago, skippydiesel said:

This debate started around Turb's suggestion that TBO could be used as a comparative measure of engine service reliability (paraphrase) - I don't think it can due to the influence of the various engine manufacturers marketing department on the TBO times generated - way to much hope & a prayer generated by differing faiths 😄

That was based on a common TBO standard like 2000 hours

Even if manufacturer A has a TBO of 1100 hours and manufacturer B states 2000 hours you can make a judgement on what to buy.

Just to complicate matters, if every Manufacturer engine made 1100 hours, and Manufacturer B engines were only surviving for between 800 and 1000 hours, manufacturer A would be the more reliable.

 

It comes down to what data you can obtain reliably and this usually comes from service departments and repair shops. 

 

The manufacturer may have tested several hundred engines and achieved a safe TBO target, but once the operators and repairers start working them they might not live up to the testing.

 

So I would rely more on what the engines are actually achieving.

[facthunter]

Properly established TBO times WOULD be a  way of comparing aero engine life in broad terms. If enough don't make the figure, It USED to be appropriately reduced till any obvious problem(s) were rectified and the results evident, when it would be reinstated.  Nev.

Edited December 4, 2023 by facthunter

[skippydiesel]

"It comes down to what data you can obtain reliably and this usually comes from service departments and repair shops" -  Agreed but how to access & turn into data that can be used for genuine (level playing field) comparative analysis?

 

".....common TBO standard like 2000 hours" - the problem is, it can not be a "standard" if every manufacturer is using different criteria. I may be wrong but it seems to me that the main players all went to 2000 hrs (some higher) within a few years of each other. Sure this could be explained by technological improvements, historic time in service/repairs, etc but to me it's a tad too convenient.

 

"The manufacturer may have tested several hundred engines and achieved a safe TBO target, but once the operators and repairers start working them they might not live up to the testing". - There has always been a problem translating bench/lab, even manufactures test running, into real life data. Test conditions are usually close to ideal ie not with the variables of real life operating.

 

So I would rely more on what the engines are actually achieving. - Agreed, however this would require the manufacture to encourage feedback from service/repair facilities , THEN be willing to make the accumulates data/conclusions available to the public

 

Just guessing - TBO claims are not warranties ie not backed by any sort of financial support, in the event of engine problems that occur before TBO  Ripe for the marketing department to inflate claims to equal/exceed the competition.

[skippydiesel]

The lack of standardised testing & reporting - 

 

Leaves the engine manufacturer at the mercy of the rumour mill/urbane myth (can work +/-).

It can also mean that the maker is less likely to improve the product - might just price it to get sales.

[turboplanner]

40 minutes ago, skippydiesel said:

"It comes down to what data you can obtain reliably and this usually comes from service departments and repair shops" -  Agreed but how to access & turn into data that can be used for genuine (level playing field) comparative analysis?

 

".....common TBO standard like 2000 hours" - the problem is, it can not be a "standard" if every manufacturer is using different criteria. I may be wrong but it seems to me that the main players all went to 2000 hrs (some higher) within a few years of each other. Sure this could be explained by technological improvements, historic time in service/repairs, etc but to me it's a tad too convenient.

 

"The manufacturer may have tested several hundred engines and achieved a safe TBO target, but once the operators and repairers start working them they might not live up to the testing". - There has always been a problem translating bench/lab, even manufactures test running, into real life data. Test conditions are usually close to ideal ie not with the variables of real life operating.

Correct; so good reason not to use arbitrary TBO, but focus on what each engine is costing and downtime per engine.

When you put an engine into any Application however, there is a need for it to achieve a certain result or the Application makes financial losses. So an airctraft engine for training needs to achieve x hours to maintain a profitable business. 

40 minutes ago, skippydiesel said:

 

So I would rely more on what the engines are actually achieving. - Agreed, however this would require the manufacture to encourage feedback from service/repair facilities , THEN be willing to make the accumulates data/conclusions available to the public

The way I've been doing it since 1981 is person to person contact with the people responsible for R&M work and budget. So you get real times from the cards and real costs from the invoices. If they practice Unit Costing, usually these details have already been entered in a spread sheet for each unit and there is a TOTALs speadsheet that allows you to compare each one vs the average, or between two different makes, or between those with carbies on top and the others etc. That data was used to choose correct specifications for applications, Whole of life costs etc. One company had developed their own software which was so accurate they could tell when someone was putting a packet of smokes on the bill when he was filling up.

Manufacturers have a moral obligation not to give out the IP of their customers, and I think you said you wouldn't believe it anyway, so it's best to talk to the workshops about one aircraft at a time. Getting the data on 50 to 100 doesn't take long.

40 minutes ago, skippydiesel said:

Just guessing - TBO claims are not warranties ie not backed by any sort of financial support, in the event of engine problems that occur before TBO  Ripe for the marketing department to inflate claims to equal/exceed the competition.

Another reason to make decisions based on cost and downtime.

[facthunter]

When a part fails a proper examination of it should find the reason why it happened. If it's faulty heat treatment  or a scratch on a radius on the crankshaft or a design weakness. Not having a spark plug tensioned correctly or the wrong heat range. A piece of incandescent carbon can cause a run on or detonation or it can lodge under a valve next start. Operating in a dusty environment can reduce engine life. Light bore surface rust can pug up rings. Short engine runs can put water in the oil,. Also running the engine with oil temp too cool. Plenty of variables.  Nev

[turboplanner]

For those who've never done Unit costing or had trouble was just a depiction of cost centres which you could apply to soup makers or TV sets, Chart A is its equivalent, marked "Aircraft".

I just picked 4 cost centres to make it simple; the columns are not loaded so not to scale.

Chart A reads from all the other sub-charts.

In this case R&M looks high.

 

Chart B

This is the R&M sub group, I've limited it to two subjects, but nothing to stop you having 20.

In this case the problem seems to be in the Engine category.

 

Chart C

This is the engine sub group.

I've just picked 4, but you could have many such as electrical system, fuel system, oil supply system accessories etc.

In this case the first three look to be isolated but camshafts are out of control.

 

Chart D etc

I haven't drawn this but somewhere along the way the costs are isolated by make, model and the location they are operating.

 

Conclusion

We know that make X has an endemic problem with camshafts spread across all airfields surveyed and we have to make a decision to either work with the Manufacturer (warranty, out of pocket costs) or buy something else.

 

In most cases you see the pattern forming very early in the interview process, and the benefit of doing this is that you know the exact truth rather than relying on corporate propaganda or social media.

 

 

 

 

 

[facthunter]

Talk to aircraft mechanics as they work with  this stuff but IF you don't know much about engines generally they won't be very interested in doing it.   It has to be a 2 way thing. Like Bert Flood and I both had a motorbike background. Flood was BIG into Bultaco's and had 2 sons racing motor cross.  Before I started flying I spent a heap of time in RNAC's engine shop. I've always spent time with the people who fix this stuff.. You get to know what's REALLY going on that way. Places like OSHKOSH are a vendors  shopfront within a very aeroplaney  atmosphere that charges your enthusiasm Batteries. and might do a good job at emptying your pockets.  Nev

Edited December 5, 2023 by facthunter
more content.

[LoonyBob]

7 hours ago, skippydiesel said:

 I haven't really been involved in certified aircraft for about 15 years so got no idea - my intersted & I suggest, that of most small aircraft owners is how reliable (safe & minimal down time) is it and how much will it cost me to operate. 

 

As for your earlier comment - "Ahem. For a Certified engine, TBO refers to the core; "tops" are just an incidental." - The industry can come up with whatever convention it may wish (to justify a poor product) however I don't accept  that a routine (ie expected/scheduled) substantial rebuild (starting from the core) can be considered anything less than a partial/total recondition. If an engine model is subject to this level of pre TBO intervention it is not making the manufacturer's claimed TBO.

 

 

 

From the Chicago Convention of 1922 to the Chicago Convention of 1944, it was hammered out that Airworthiness is defined in terms of "Acceptable Probability of Failure", and that Airworthiness is achieved by: Control of Design; Control of Manufacture; Control of Maintenance; Control of Operations; and Control of Training.

 

Your argument is economic; your position is that you bought the engine, you don't want to spend significant money on it until the TBO is reached. Bad luck; the engines for London Buses were designed that way; but that is NOT how safety is achieved in aircraft that are light enough to fly.

 

It boils down to the physics of flight; there would be no turboprops if empty weight / MTOW ratio were not the penultimate expression of aircraft effectiveness....

Edited December 5, 2023 by LoonyBob

[spacesailor]

YES

There was a ' diesel motor ' that ' always ' made TBO .

AND 

That was its downfall .  It only sold one engine per van, then had  no spare parts to sell either .

 The name eludes me , possibly " Trojan " .

spacesailor

[facthunter]

If it is it's  a Trojan it's one crazy vehicle built in the land of Jowett cars and Scott motorcycles.  Nev