EC225 crash near Bergen, Norway April 2016

[Concentric]

Originally Posted by birmingham

any ideas what they are trying to establish? I would think there are very few if any still operating in Europe

So, what if they find such particles? – Conclude that the Type B gear/bearing spalls at or before 300 FH? That wouldn’t be good, would it?

Or, what if they don’t find any? – Eureka!? Or maybe ‘Hey Presto’? The Type B’s are safe??? Try again at 600 FH, 900 FH etc…?

For the 300 FH to have significant meaning the cooler would have to have been flushed when the MGB/epicyclic module/2nd stage planet gears were installed. Is that normal procedure? If not, I don’t think the specific FH would be the important factor here. How about flushing the MGB casing too?

In exchanging all Type A planet gears for Type B’s last year, AH must have accumulated a large sample of used Type A's for metallurgical inspection. Perhaps the answer is that this latest measure is to now, selectively, acquire a sample of Type B’s that have begun to spall and put them under the microscope too.