Quote from: testguy on 07/07/2019 04:31 pm Anyone care to speculate if the stator issue was related to the 600 Hz resonance? It would be great if it was.

The speed of sound in steel (ballpark of whatever superalloy is involved) is just under 6 km/s- 600hz would be a resonance of a steel part 10m long, if I understand that math correctly. (I might not be)



The fire comes out the big end, right?

Seems that if its not resonance in metal and if we can clearly hear it at significant distance the resonance is within the combustion gas. But at the point we're hearing it the engine is shutting down and the conditions in the flow path are changing greatly. Does it only happen during that transient condition and the shutting down is when the damage occurs or does it happen during continuous operation and our hearing it during shutdown is an outgrowth of that?[side pondering that nobody has an answer for: if an engine has a latent tendency to resonate and you attach a number of them to a structure how likely would it be that one going into resonance at that problem frequency would through the structure get others resonating]Yes.