Engine Dependability

On Mon, 19 Apr 2004 15:37:43 -0500, O. Sami Saydjari wrote:



Greg Copeland wrote:

On Mon, 19 Apr 2004 13:53:36 -0600, Newps wrote:


"Greg Copeland" wrote in message
news


Well, I guess that puts us back to the original question. I, like the
orginal article's author, thought historical statistics were used to
establish TBO numbers. If no one is tracking this information, where do
the TBO numbers come from? Insurance liability statistics from wrecks?

TBO comes from two places.

1) Marketing

2) A Guess


LOL! Is anyone else bothered by this? I guess it's not really saying
MTBF, it's just saying, your engine is ganna be tired when it hit this
number. So, I guess that really isn't all that bad after all.

I, for one, prefer to base my decisions on facts instead of
speculations. How do they know the engine will be tired after x hours?
What does tired mean? The only thing that would be meaningful to
owners is probability of failure at X hours.

It does not seem that collecting the data and calculating MTBF would be
that hard.

I sure hope the engineers who designed the engine did not use the same
attitude with respect to the components they used! "Crankshaft A is 20%
cheaper than Crankshaft B? Well, who cares, everyone knows that
everyone just makes the reliability numbers up anyway. Let's use
Crankshaft A." Arg!




Well, there's no doubt that having an MTBF number with each engine would
be nice to know, but I doubt you're going to get enough sampling from this
group to even begin to eliminate noise. So, until someone is able to
create a meaningful MTBF number for us, the TBO is the best we have.
Which means, exactly what it says. It says, after x-number of hours, you
should be considering an overhaul of the engine. I don't believe it
speaks to anything else. In other words, one can assume it means, should
you actually reach TBO without requiring an overhaul, at x-hours, you
should be considering it.