Airplane ownership as an investment??

DavidWhite said:
When I am done with college (2 years cc and 2 years at a 4 year college) my parents will have spent half of what it would cost to send me to ERAU for 4 years - I will finish with twice as many hours and all the same ratings. (and a plane)
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Extremely smart. 4 year college is a huge rip off. The books are 3x as expensive and the instruction is the same or worse for your first 2 years taking all those BS classes.
 
wabower said:
Whoever is bank-rolling that deal should be even prouder. :wink2::D
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Well, I'm still waiting for your donation to make the engine overhaul happen. ;)

Plane's about done with its annual. Engines both came back good, so we'll plan to keep them going for a bit yet. Doubly so since we haven't gotten the donations we need to do the overhauls yet.
 
Ted DuPuis said:
Wayne got it right. I really don't care which - both can fail.
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If the objective is to minimize risk, always choose the option with the lowest probability of failure. The observation that an engine can fail at any number of hours isn't useful if the probability of failure varies with time.

If the objective is to profess a fatalistic view of life, buy the cheapest crap you can find because you believe the universe is out to get you and its going to kill you anyway, or cost you a lot money (if it lets you live.)
 
Jim Logajan said:
If the objective is to minimize risk, always choose the option with the lowest probability of failure. The observation that an engine can fail at any number of hours isn't useful if the probability of failure varies with time.
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Exactly.
 
Jim Logajan said:
If the objective is to minimize risk, always choose the option with the lowest probability of failure. The observation that an engine can fail at any number of hours isn't useful if the probability of failure varies with time.
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And as I recall your highest probability of engine failure was in the first couple hundred hours, then it dropped off and stayed pretty much level after that. Perhaps someone else has the graph available that shows the statistics. But statistics don't help if you're flying the plane that's an outlier - a 1% chance of death doesn't mean you're only 1% dead.

SMOH is only one of many factors that impacts whether or not the engine you are flying is likely to fail on you. Far more than that would have to do with the quality of components and of most recent overhaul. Who did the overhaul? Was it a quality shop or could my dog do better work? I've seen overhauls that have all the logbook entries to be legal, but that I wouldn't put in my lawn mower.

Next, how's the maintenance been on the engine? Did the owner put oil in and just run it, or did they actually do oil changes at recommended intervals (or sooner)? I know people who've done 200-hour oil changes, and people who do 25-hour oil changes. While I think 25 is a bit excessive (unless you've got one of the engines that only has oil screens), the 200-hour oil change is definitely well past due. Were the plugs ever cleaned? Did the operator run the engine at 25 ROP and peak CHT, or at some better mixture setting that kept the cylinders at a happier temperature?

There are many pieces to the puzzle that are missed by simply looking at hours...
 
Ted DuPuis said:
And as I recall your highest probability of engine failure was in the first couple hundred hours, then it dropped off and stayed pretty much level after that. Perhaps someone else has the graph available that shows the statistics.
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From these articles:
http://www.avweb.com/news/savvyaviator/savvy_aviator_45_how_risky_is_going_past_tbo_195241-1.html
http://www.avweb.com/news/savvyavia...ered_maintenance_part_2_195969-1.html?type=pf
195241_ntsb_engine_failure_data.gif

But statistics don't help if you're flying the plane that's an outlier - a 1% chance of death doesn't mean you're only 1% dead.
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It only makes sense to make the above point if the reading audience is believed to have no sense of the meaning of probability. Otherwise it does nothing other than undermine any attempt to minimize risk by appeals to fatalism. Repetition of bad reasoning doesn't improve it.

SMOH is only one of many factors that impacts whether or not the engine you are flying is likely to fail on you. Far more than that would have to do with the quality of components and of most recent overhaul. Who did the overhaul? Was it a quality shop or could my dog do better work? I've seen overhauls that have all the logbook entries to be legal, but that I wouldn't put in my lawn mower.

Next, how's the maintenance been on the engine? Did the owner put oil in and just run it, or did they actually do oil changes at recommended intervals (or sooner)? I know people who've done 200-hour oil changes, and people who do 25-hour oil changes. While I think 25 is a bit excessive (unless you've got one of the engines that only has oil screens), the 200-hour oil change is definitely well past due. Were the plugs ever cleaned? Did the operator run the engine at 25 ROP and peak CHT, or at some better mixture setting that kept the cylinders at a happier temperature?

There are many pieces to the puzzle that are missed by simply looking at hours...
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These are all reasonable points, and to the extent that answers can be had, they should be obtained and weighted. But it would be better to examine the engine and make objective measurements.
 
Jim Logajan said:
195241_ntsb_engine_failure_data.gif
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So if you were to go purely on that, the 2200-hour engine is a better choice, and that 2500-2999 hour engines are the most reliable.

Of course, what what it doesn't tell you is what percentage of the flight hours are flown by aircraft with engines in those ranges. Unfortunately there isn't an engine reliability database that really includes the necessary indicators to give good statistics. There aren't nearly as many engines out there with 2000+ hours SMOH as there are engines with 1000-2000 hours SMOH, since most engines will get replaced closer to TBO (if not before, assuming they were in the category of engines that failed early or were giving indicators of being close to failure).

It only makes sense to make the above point if the reading audience is believed to have no sense of the meaning of probability. Otherwise it does nothing other than undermine any attempt to minimize risk by appeals to fatalism. Repetition of bad reasoning doesn't improve it.
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I'm not sure how you come to the conclusion that I'm supporting fatalism when I've come up with a number of things to look for, and that's only a start.

What I do believe, though, is that anyone who gets into a mental comfort zone regarding engine reliability simply due to hours SMOH is fooling themselves. That's where that 1% thing comes in.

These are all reasonable points, and to the extent that answers can be had, they should be obtained and weighted. But it would be better to examine the engine and make objective measurements.
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These are part of examining the engine to make an objective measurement.
 
I think the main problem with high time engines is not that they are going to outright fail tomorrow but that they will develop problems which will cause need for replacement sooner rather than later. I don't think it's useful to think that on any given day a high time engine has a meaningfully higher rate of failure compared to a new engine.
 
Everskyward said:
I think the main problem with high time engines is not that they are going to outright fail tomorrow but that they will develop problems which will cause need for replacement sooner rather than later. I don't think it's useful to think that on any given day a high time engine has a meaningfully higher rate of failure compared to a new engine.
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As usual, summarized more eloquently than I am capable of. Thank you, Mari. :)
 
On the TBO question

There is failure where it stops spinning and failure where I don't return it to service after an annual.

I'd warrant that younger engines are more prone to the first kind of failure and older ones the second.
 
On the investment front my airplane was my best performing asset when 2008 happened,


It lost the least value.
 
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