What was found
NR 2 BLEED TRIP OFF LIGHT ILLUMINATED AT FL 380, RESET IAW QRH. LIGHT REMAINED EXTINGUISHED. WHEN LIGHT CAME ON, LEFT DUCT PRESSURE 35 PSI, RIGHT 10 PSI. BOTH AT 35 PSI AFTER RESET. ACFT GROUNDED. ACCOMPLISHED ENGINE BLEED AIR SYS HEALTH CHECK IAW T/C NG-NG-36WC-00001. WHILE ACCOMPLISHING HEALTH CHECK , THE NR 2 ENGINE PRECOOLER CONTROL VALVE FAILED STEP 03.F. REMOVED AND REPLACED THE NR 2 ENGINE PRECOOLER CONTROL VALVE IAW AMM 36-12-02-000-801, AND AMM 36-12-02-400-801. LEAK AND OPS CHECKED GOOD. WHILE ACCOMPLISHING HEALTH CHECK THE NR 2 ENGINE HIGH STAGE VALVE FAILED STEP 04.K. REMOVED AND REPLACED THE NR 2 ENG HIGH STAGE VALVE IAW AMM 36-11-06-000-01, AND AMM 36-11-06-400-801. LEAK CHECKED GOOD. ACCOMPLISHEID BLEED AIR CROSSOVER OPERATIONAL TEST IAW AMM 36-11-00-710-801. OPS CHECKED GOOD.