What was found
ON THE GROUND WITH BOTH ENGINES RUNNING AND BOTH PACKS IN AUTO, LT DUCT PRESSURE INDICATES 5 PSI AND WILL NOT INCREASE AS POWER IS ADVANCED. RT SIDE NORMAL 20 PSI AT IDLE AND INCREASING AS POWER ADVANCED. R & R NR 1 HIGH STAGE REGULATOR IAW AMM 36-11-07. GROUND RAN ENGINE SAME FAULT EXISTS. R & R HIGH STAGE VALVE IAW AMM 36-11-06. GROUND RAN ENGINE AGAIN FAULT STILL EXISTS. TROUBLESHOT PNEUMATIC SENSE LINES AND FOUND SENSE LINE FROM PRSOV T FITTING THROUGH 450 THERMOSTAT LEAKING. REMOVED LEAKING LINE. INSTALLED NEW PNEUMATIC LINE FROM PRSOV T-FITTING TO 450 SENSOR. GROUND RAN ACFT AND BLEED SYS NO FAULTS FOUND. ALL OK FOR SERVICE.