What was found
LEFT PNEUMATIC PRESSURE 20 PSI HIGHER THAN RIGHT PNEUMATIC PRESSURE ON CLIMB, LEFT 40 PSI, RIGHT 20 PSI. IN CRUISE, LEFT 40, RIGHT 25. ACFT GROUNDED. PERFORMED TROUBLESHOOTING ON THE NR 2 ENGINE PNEUMATIC SYSTEM IAW MG-36WC-00001 AND FIM TASK 36-10, TASK 805. FOUND THE BLEED AIR REGULATOR DEFECTIVE & THE PRECOOLER VALVE DEFECTIVE. REPLACED THE BLEED AIR REGULATOR IAW AMM 36-11-03-400-801. REPLACED THE PRE-COOLER CONTROL VALVE IAW AMM 36-12-02-400-801. PERFORMED THE REPAIR CONFIRMATION IAW FIM TASK 36-10, TASK 805, STEP H. NO DEFECTS NOTED. BOTH NEEDLES PAIRED AT 42 PSI.