When addressing wear in blade root slots of a high-pressure turbine, what methods are used to restore the slots?

• A. Grinding the slots to remove wear without replacement.
• B. Replacing the blade entirely regardless of wear.
• C. Slot repair or replacement per OEM guidelines; reaming, welding or coating film application; typically replacement if wear exceeds limits.
• D. Ignoring wear and continuing operation.

Answer: (C)

Wear in blade root slots changes the fit and alignment of the blade, so restoration must follow the system’s established repair and replacement guidelines. When wear is minor, reaming restores the slot diameter and roundness to meet exact tolerances, allowing the blade to seat correctly again. If the wear is more extensive, rebuilding the worn areas through welding or material buildup can restore the original geometry, after which the slot is re-machined to the correct profile. A coating film or other protective coating can be applied to reduce future wear and protect rebuilt surfaces. If wear has progressed beyond the OEM-specified limits, replacement of the blade (or the root portion) is typically required. Grinding the slots to remove wear isn’t preferred because it can remove too much material or alter critical tolerances, replacing the blade when wear is within limits isn’t necessary, and ignoring wear is unsafe.