What was found
DURING CLIMB OUT, NOTED RT PACK 18 PSI LOWER THAN LEFT. AT CRUISE THEY WERE MUCH CLOSER. DESCENT & ON GROUND THE RT PACK 18 PSI LOWER THAN LT PACK. VERBAL FROM PILOT ON GROUND RT PACK AT 2 PSI, LT 20 PSI. ACFT GROUNDED . REMOVED AND REPLACED THE HIGH STAGE VALVE AND HIGH STAGE REGULATOR ON THE NR 2 ENGINE. ACCOMPLISHED ENGINE BLEED AIR CROSSOVER OPS TEST IAW AMM 36-11-00-710-801. ALL PRESSURE VALUES AT ALL N1 SETTINGS FOR NR 1 AND 2 ENGINES WERE WITHIN SPECIFICATIONS.