It looks like operators will have to remove all their P&W powered B777s from service until they have checked the engines. Since the problem seems to be fatigue (which is a function of time) in a front fan blade, why not just replace all the blades in the front fan while you have it in maintenance? What would be the cost of that compared to an inspection?

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    $\begingroup$ The cost would be significant. Those blades are usually inspected one-by-one at one of the checks, and any failing blades are replaced. Replacing an entire fleet of blades would be huge, especially since you need to disassemble them anyway. $\endgroup$ – Ron Beyer Feb 26 at 20:16
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    $\begingroup$ How do you expect that replacing the whole engine fan is less expensive than an inspection? $\endgroup$ – ocirocir Feb 26 at 20:16
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    $\begingroup$ It would probably take P&W a really long time to produce enough blades to replace every one in service on every engine on every 777 in the world. They're not cheap to produce, and it would be an immense expense to have thousands of them sitting unused in a warehouse, expecting (hoping) to never need most of them, as a "just in case" contingency. $\endgroup$ – Ralph J Feb 26 at 20:34
  • $\begingroup$ I didn't mean to imply I thought replacing would be cheaper than inspection, I was thinking more along the lines of "the blades already have thousands of hours on them, even those that test ok may be getting near the end of their life, why not replace them all now then you won't have to worry about them for a long time." $\endgroup$ – Flynn Feb 26 at 20:58
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    $\begingroup$ "why not replace them all now then you won't have to worry about them for a long time" ? Well, just because they may have 1000's hours MTTF (mean time to failure), that's not a point in time; it's a distribution for the Failure rate. That's why everything gets inspected on regular schedules and after unexpected events. If you replaced them all at 80% MTTF, you'd be discarding good parts and still have failures. Discovering imminent failure by inspection way cheaper than by observation. $\endgroup$ – Ian W Feb 27 at 11:03

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