What was found
PNEUMATIC DUCT PRESS 20 PSI DIFFERENCE IN CRUISE. LT PNEUMATIC PRESS 42 PSI. RT PNEUMATIC PRESS 22 PSI N1 89.8 ALT FL 350 BOTH BLEED SWITCHES ON/BOTH PACK SWITCHES AUTO BOTH RECIRC FANS ON A/I OFF. ACCOMPLISHED NR 2 ENG BLEED AIR SYS HEALTH CHECK IAW T/C NG-36WC-00001. PRECOOLER CONTROL VALVE FAILS TO OPEN BY 3PSIG AND NO OTHER DEFECTS NOTED. REPLACED NR 2 ENG PRECOOLER CONTROL VALVE REF AMM 36-12-02-000-801 & 36-12-02-400-801. LEAK CHECK GOOD. GROUND VERIFICATION OF THE ENGINE BLEED AIR CROSSOVER OPS TEST CHECKS GOOD REF AMM 36-11-00-710-801.