What was found
DUCT PRESSURE DIFFERENTIAL EXCEEDS 20 PSI. DURING CLIMB RIGHT DUCT SHOWS 50-55 (55), LEFT SHOWS 20-25. ACFT GROUNDED. ACCOMPLISHED ENGINE BLEED AIR SYSTEM HEALTH CHECK ON NR 1 ENGINE THRU STEPS 5, STILL REQUIRES STEP 6, OPERATION TEST. REMOVED AND REPLACED PRECOOLER CONTROL VALVE, IAW AMM 36-12-02 AS DIRECTED BY TASK CARD NG-36WC-00001 STEP 03.F.(6). OPS CHECKED GOOD. REMOVED AND REPLACED BLEED AIR REGULATOR, IAW AMM 36-11-03AS DIRECTED BY TASK CARD #NG-36WC-00001 STEP 03.D.2(C). OPS CHECK GOOD. COMPLETED T/C NG-36WC-00001, OPS CHECKED GOOD.