What was found
FL 370, DUCT SPLIT LEFT 24 PSI RIGHT 44 PSI. PERFORMED NR 1 ENG BLEED AIR SYS HEALTH CHECK IAW MM 36-11-00. FOUND SEAL AND COUPLING AIR LEAK WHERE PRECOOLER UPSTREAM DUCT CONNECTS TO PRECOOLER. REPLACED SEAL. LEAK CHECKED GOOD IAW MM 36-12-01. DURING HEALTH CHECK HIGH STAGE VALVE TEST FAILED. REPLACED HSV. HSV TEST PASSED IAW MM 36-11-06 & 36-11-00. PNEUMATIC SYSTEM RESTORED FITTINGS/DUCTS LEAK CHECKED GOOD. HIGH POWER RUN ACCOMPLISHED IAW MM 36-11-00-710-801. ENGINE BLEED AIR CROSSOVER OPS TESTED GOOD. ALL PRESSURES N1 IDLE 80% NEEDLES WITHIN +/ 2 PSI AND STABLE AT HIGH POWER ISO VALVE CLOSED.