What was found
CABIN HIGH ALTITUDE WARNING AT 9,999 FT, COMPLETED RAPID DESCENT TO 9,000 FT. SWITCHED SYS TO MANUAL AND THAN BACK TO AUTO. NR 2 SYS RETURNED TO NORMAL. TROUBLESHOT IAW SRM TSM 21-31-00-810-827. REPLACED CPC 1 AND CPC 2 REF AMM 21-31-34 PB 40. OPS CHECK NORMAL.