What was found
WITH LT ENGINE RUNNING AND LT ENG BLEED SWITCH OFF, LT SIDE DUCT PRESSURE SLOW TO DROP, STOPS AT 3-5 PSI ON LEFT SIDE AND DOES NOT GO TO ZERO. RT SIDE BLEED OPS NORMAL. R&R THE LT ENGINE PRSOV PER AMM 36-11-04-401. AFTER REPLACEMENT DURING ENGINE RUN WITH RT SIDE ISOLATED AND APU VALVE OFF LT DUCT PRESSURE SHOWS 5 PSI WITH THE LT BLEED SWITCH IN THE OFF POSITION. ROTABLE PARTS CHANGE WAS INDICATED TT 1023589 SN OFF 4082 VALVE, PRESSURE OFF 29-3612-9-0004 4082 ON 29-3612-9-0004 0548 NO HELP. REINSTALLED ORIGINAL INDICATOR AND TRANSDUCER. REPLACED DUCT PRESSURE INDICATOR AND PRESSURE TRANSDUCER. BOTH REPLACED LT ENG BLEED AIR REGULATOR PER AMM 36-11-03 ROTABLE PARTS CHANGE WAS INDICATED TT 1333371 SN OFF 4092 REGULATOR, BLEED OFF 29-3611-9-0005 4092 ON 29-3611-9-0005 0912 PERFORMED FIM TASK 36-10-00-810-802. RAN BOTH ENGINES AND FOUND DUCT PRESS DECREASE BOTH ENGINES AS REQUIRED. REPLACED LT DUCT PRESS TRANSDUCER PER AMM 36-21-01-400-801, PRECAUTIONARY. DUCT PRESS FOUND LESS THAN 3 PSI WITH ENGINE BLEED OFF. DUCT PRESS WITHIN PARAMETERS PER FIM 36-21-01-400-801.