What was found
THE ACFT HAD A CABIN ALTITUDE WARNING AT FL350. PERFORMED AN EMERGENCY DECENT, AND DIVERTED. ON THE GROUND PERFORMED TSM 21-31-00-810-809-A, AND FOUND THAT BOTH AIR PACK FLOW CONTROL VALVES WERE CLOSED. PERFORMED AMM 21-31-00-710-002-A, 21-31-00-710-003-A, AND 21-61-00-710-001-A WITH NO ABNORMALITIES NOTED. NR 1 & 2 EIU`S WERE REPLACED AND THE AIRCRAFT WAS RETURNED TO SERVICE.