falls in the interval WL d1 UCL1,\...\ a second sample with size n2= 73 \...\is taken, where 7 non-conforming items are present, i.e. d2= 7\...\ (see Table 7) For this sampling stage, since d1+ d2= 9\...\ exceeds UCL2= 5.5\...\ (or d1 d2 UCL2),\...\ the first out-of-control signal is issued. Another out-of-control signal is detected at sampling stage 13 as d1+ d2= 6\...\ is greater than UcL2 =5.5.\...\ Actions are initiated to check the underlying process and remove the assignable causes that trigger the out-of-control signals