Finally, some sense!

[cnpeters]

The purpose of a TBO is to give you the best estimate of trouble-free hours without fear of failure.

The trouble is finding data that really supports this estimate. It may be a best guess, or one designed to enhance revenue and promote factory rebuilds. There is a growing push in medicine to prove (or disprove) conventional wisdom that has been passed down through medical training for decades as being gospel. Evidence is what we are pushing in medicine, and what we lack in determining engine longevity.

Why fly your engine up to it's failure point, or closer than necessary?

The problem is the lack of data showing where the failure point exists. And, of course, it would not be a point, but an increase in probability. But it is exceedingly difficult to show what that rate is.

Same goes for airline pilots. Why work a guy until he drops dead? I for one, want to enjoy my retirement, and 60 sounds like a good age to start. Is 65 any less of a random age than 60? How about 70, wouldn't that be random too?

There are many pilots who want to work beyond 60, and can prove through testing that they possess full mental and physical abilities to perform the job.
Now we have plenty of solid data to support this in the medical field.

How many 65 year old doctors do you work with, Milt? Do you want to practice to 65? Seems like I heard you say recently you are on your way out???

I know of many docs who love their work and continue way past 65. Unfortunately, the younger crowd will unlikely follow suit in the same numbers given the state of medicine today.

From a doctor who loves evidence... .

[N395V]

I should have known this was just another thinly disguised pitch for GAMI injectors

Gee maybe I should ask them for a referral fee. Unfortunately I got my injectors from AFP and not GAMI so I suspect any hope of a commission is off the table.

how inadequate the Lycomng offering is to your opinion that they might last forever!

Twin Cessnas including mine have Continentals.

Now my F1 has a Lyc running LOP (Not with GAMIs) and while I do not expect it will run for ever I am confident it will pass 3000 hrs.

On the other hand I just had a brand new M14 poop out on me at 82 hrs.

As the good doc noted above all Mike Busch and many others are looking for is realistic data.

I think you can make a valid argument that TBOs are just another pitch by Lycoming and Continental to sell engines and parts.

[jcoloccia]

Originally Posted by Yukon

You bet Milt, with 300,000 Lycomings in the field, and at least as many Continentals, I'm sure 15 of you are on the MFG's speed dial. Coming from Avweb, I should have known this was just another thinly disguised pitch for GAMI injectors.

Funny isn't it that the sentiment on the forum alternates between how inadequate the Lycomng offering is to your opinion that they might last forever!

Well here's to early retirement! See you at the hangar!

Did you even read the article? It has nothing to do with LOP, injectors, or even engine operating procedures. It was an objective look at accidents in the NTSB database....i.e. it was data.

Instead of stirring the pot with bad and innacurate sarcasm, why don't you actually read the article and/or bring some data to the table that we can look at and debate?

This forum is a great opportunity to exchange information and opinions, so much so that even the brilliant among us...those who know exactly how engines behave and fail and precisely when airline captians should be made to retire....might learn something if they participate.

[Yukon]

Milt,

What was the cause of your M-14 failure?

[grantcarruthers]

Originally Posted by Yukon

If you think engines should be run indefinitely on the advise of writers and doctors and others who doubt the good intentions of the manufacturers,
then have at it.

I think you've once again missed the entire point so as to have a chance to jump up on your soapbox again.


The take home from the article IMHO is that CATASTROPHIC failures are rare due solely from age and TSOH and that if you are careful to look for and listen to the evidence your engine is giving you it is likely safer to go past TBO for some time rather than jump into the most dangerous period of an engines life with a fresh overhaul. And he (MB) is most certainly NOT advocating running an engine infinately as you quite clearly and inaccurately imply to try and make your argument seem even slightly valid.

Quit misquoting and borderline lying about others opinions and statements please. Your misinformation tarnishes an otherwise valid opinion that overhaul at TBO is the right choice for some people based on their risk management beliefs.

[Yukon]

Dr Peters,

For the most part, engine failure data is in the public domain, on the FAA and NTSB websites, as most failures cause a crash. Take a look at the SDR's and you will see that airplane engines that run 3000 hours are in the vast minority. It is the experience of most operators that Lycomings and Continentals need one or more cylinders prior to TBO. At TBO, most engines require valve guide replacement, main and rod bearings, and lots of cylinder rework. Surely, an owner-flown aircraft operated at 55 percent power will exhibit better longevity. Unfortunately, most hours are flown by commercial operators, at higher power settings, and TBO's are predicated on their experience.

It is not the responsibility of the manufacturers to publicly disclose their proprietary data. Nobody's getting wealthy in the aircraft engine business. If it weren't for the deep pockets of major corporations like Textron and Teledyne, we'd all be on foot. If a 2000 hour engine doesn't suit your needs and expectations, install a Mazda rotary or a Subaru. I hear they are real smooth and run forever.

[Yukon]

Grant,

The Avweb writer is currently 750 hrs past TBO. Is it your contention he is doing so because he is afraid of the statistics related to break-in failures? As everybody knows, the engine failure fatality rate in light twins is twice that of singles, so IMHO this guy is being very irresponsible.

Yes indeed, lot's of failures immediately after overhaul, but mostly related to human error (loose hoses, mis-installed parts). Just look at how many of our members are teaching themselves engine overhaul, while building their plane. I'm sure that factory-remans run in a test cell exhibit very acceptable first-flight failure rates.

[szicree]

Interesting info from all parties but I just can't buy into the author's argument. On the one hand, he is saying that avoiding the rebuild for a while longer keeps me out of the most dangerous part of the engine's life cycle. Ok fine, but I do have to rebuild eventually, right? So all I do is pospone the inevitable. Additionally, the graph presented by the author (WAG) seems to show a very slight increase in failure rates as the engine goes past TBO. So to avoid an inevitable increase in risk I am supposed to take a risk? The assertion that the author has not seen one scintilla of evidence to support the wisdom of TBO is true, but it's only because he hasn't been allowed to see it. The conspiracy theorists would like me to believe that Lycoming establishes TBO numbers in order to boost revenue, but I would bet the farm that they are based simply on average wear rates for things like rod bearings and valve guides. The idea of TBO is to rebuild before there's a problem of any kind. If you wait for metal in the oil you have just flown with a problem engine and are perhaps looking at a crank grind. Think about brake pads on the family car. Do you wait for the squealing to start? You change em' when they're near worn out. This can be seen, but bearing wear can't. I have a lot of trouble believing that the data on this is such a closely guarded secret. There are several professional engine builders on here that could probably give figures for what amount of wear they see on engines with x number of hours. Meanwhile, looking at accident reports for engine failure seems like a complete waste of time. I mean, suppose somebody tells you that you can expect an engine failure after exactly 2500 hrs. Are you gonna run it to 2499? 2400?

[osxuser]

Originally Posted by Yukon

Dr Peters,

For the most part, engine failure data is in the public domain, on the FAA and NTSB websites, as most failures cause a crash. ...

Based on what? That is a VERY broad statement, I don't know what data you have to back that up, but that hasn't been my experience.

[N395V]

Originally Posted by Yukon

Milt,

What was the cause of your M-14 failure?

Actually I am not yet certain as to the cause or whether it was the engine or the fuel system prior to the engine. It was abrupt significant power loss that occurred at the time of what should have been a modest power reduction and failure of all measures to increase power.

It was probably fuel related based upon how the engine acted and sounded.

Fuel pressure was normal, yes the plane had plenty of fuel, all the linkages to the throttle body were intact and functional and there was free flow of fuel to the firewall. I have not yet looked into the hoses for flaps or the final screen inside the throttlebody for contaminant.