What was found
DURING CLIMB, LEFT DUCT PRESSURE INDICATES 15 PSI, RIGHT DUCT PRESSURE 46 PSI, DUCT PRESSURE MATCHED WITH THRUST LEVERS AT IDLE DURING DESCENT. ACFT GROUNDED. AIR TURNBACK - PERFORMED. DUCT PRESSURE LOW, ENGINE BLEED SOURCE IAW FIM 36-10 TASK 804, H CHECKED PRECOOLER VALVE, PRSOV AND HIGH STAGE VALVE, NO DEFECTS NOTED. PERFORMED HIGH POWER ENGINE RUNS IAW AMM 71-00-00, AND CHECKED BLEED AIR PRESSURE TO N1 SETTINGS IAW FIM 36-10 FIG 305, CHECKED GOOD, NO DUCT SPLIT NOTED, PRESSURE TO N1 SETTING CHECKED GOOD, NO HISTORY.