I would get Siemens involved as soon as possible. This could be in the involvement of a Siemens tech rep or a person or firm recommended by them.
As mention in previous posts this is a complex subject and there are not that many people that can resolve your problem in reasonable time. Siemens or their designee will have an insight on all design parameters whereas others will have to develop, reverse engineer, them.
This could also be a known condition that by design/operation only affects this blade type under a particular set of conditions. I do know that turbine manufacturers tend to keep some information on design very tight, in other words you have to pry it out of them.
One thing that is very important is when you contract anyone to be available for assistance immediately if another failure should occur make sure they are there when the machine is torn down for inspection and repair. If they don’t insist on this I would look somewhere else for assistance.
If you have any failed components keep them out of peoples hands and in a protective bag, like a bubble envelope.
Another important point is to freeze all the records/data of the operating parameters when a failure occur’s. This also includes all ancillary equipment. You will find it amazing how quick the data can be corrupted or lost. Running fine is not a good answer, one needs proof.
In a failure analysis of a component, especially of rotating equipment, you have to derive the actual failure mechanism of the component and at the same time eliminate conditions that could be possible initiators of the failure. The first part normally is the easiest. The second part is usually the toughest. Every bit of information can be important to a satisfactory failure analysis.
These are machines I think Siemens should be on top of at the first sign of trouble.
