The default requirement (found in the 3rd Edition PPAP manual) is a minimum 300-piece production run. For the "initial process study" the default requirement (found in the same place) is x-bar/R charting with a minimum of 25 subgroups and 100 data points with sampling done during the PPAP production run. Either requirement may be changed to suit the circumstances, with customer approval. The expectations should always be discussed with the customer when the default requirements don't make sense.