Once again, TD thanks for the update.
My concern would be that the shafts were cooked in 'batches', and that the cooking is the required step for excluson of atomic Hydrogen. Since the Hydrogen is a result of a galvanic process, (dissimilar metals), what is the assurance that a field negative exonerates the batch? The additional ingredients involve a humid environment (prevalent), and the location at a machined in situs, (thread root). The fix per AIN is Lead formula coating, not plating, so how is the initial plating tested? The ultrasonics, per GE are only resolved to .05 inches. That is a rather large fissure, and less than that threshold leaves rather a lack of confidence, imo. So then we find that the inspections are recurring at short intervals, to protect the client from fracture and failure. Can this engine be field stripped, like the TRENT and its fifteen modules profile? I am having a time of it, picturing how any effective coating can be applied in the field, without strip. Then there are the threads.
Do you know if the threads are coated prior to join with the FFS? The suspect area is the root of the termination of the helical cut made for the thread in the shaft, again, that seems quite the challenge to "view" on wing....
Thanks TD