What was found
FLIGHT DIVERTED WITH THE NR 1 PACK TRIPPING AND NR 2 PACK ALREADY DEFERRED. AIRCRAFT LOST NR 1 PACK APPROXIMATELY 20 MINUTES AFTER TAKEOFF. NR 2 PACK PREVIOUSLY DEFERRED. CIRCUIT BREAKERS CYCLED AND PROVIDED NO HELP. REPLACED NR 1 RAI ACTUATOR (MR21603-11 WITH MR21603-67), NO HELP. REMOVED AND REPLACED NR 1 ENGINE BLEED REGULATED PRESSURE TRANSDUCER (644-1251), 8HA1 PER MM 36-11-16-401. RAN ENGINES AND OP CHECKS AND LEAK CHECKS GOOD.