you are talking risk, I'm talking cost..
Actually I'm talking cost. $18,000 worth of savings is a lot of money.
You run the risk..of higher costs beyond TBO. other wise the companies would be touting the ability to run beyond TBO.
Let's say that at overhaul I find out I need to overhaul my props and governors as well. Well, first off, I plan on overhauling my governors at TBO anyway, because they probably won't make it through another TBO. Even if I have to overhaul both props, that ends up having me breaking even. Props need to get overhauled at some point anyway, just like engines.
Now yes, if I have a crank go out and have to buy a new one, that costs me more. Then again, that would be a great excuse to upgrade to 550s.
However, you're treating TBO as a magic number, which it is not. There's nothing to say that I won't have higher costs with a low-time engine. I'm much more reluctant to put in an overhaul anything less than the best than to leave a known good past-TBO engine in.
No. They would be extending TBO. They determine where the line in the sand is. Not the FAA.
That is actually not how it works. The FAA approves the TBO as stated by the manufacturer, but that needs to be substantiated somehow as part of certification tests. If the manufacturer wishes to extend TBO, then they have to substantiate why, typically through additional testing or field service history that can be documented. The manufacturers have no motivation to tell you you can run your engine beyond TBO, because:
1) They make far more money off the 135 operators who run far more engines and run through them faster (and will need to adhere to TBO).
2) That's telling their customers not to buy products from them (i.e. "Don't buy this engine now, wait another 25% of hours first).
TBO is not a magic number. Running past it, likewise, is not magic. More than anything, TBO is an indicator.