The phrase "change to a cost accounting practice," refers to changes in the proportional measurement, assignment, or allocation of costs. Organizational changes alone do not create a change in a cost accounting practice. Where organizational changes merely result in a change to the size of the cost pool or a segment base to which the costs are to be allocated, no change in cost accounting practices has occurred. [Perry v. Martin Marietta Corp., 47 F.3d 1134 (Fed. Cir. 1995)].