What was found
AIRCRAFT WAS GROUNDED. PHL-MHT. DURING DESCENT INTO MHT FLIGHT DEVELOPED A PRESSURIZATION ISSUE. CREW DECLARED AN EMERGENCY FOR PRIORITY CLEARANCE AS A PRECAUTION. CABIN NOT PREPPED AND AFR TRUCKS DID NOT RESPOND. AIRCRAFT LANDED WITHOUT FURTHER INCIDENT. ENGINE NR 1 BLEED AIR PRESSURE WAS FLUCTUATING BETWEEN 0-60 PSI AT CLIMB POWER. THE FLIGHT DROPPED DOWN TO FL 150. THEN ENGINE NR 2 BLEED FAIL EICAS MESSAGE, WHICH WAS RESET PER QRH PROCEDURE. REPLACED HIGH PRESSURE REGULATING VALVE AND NACELLE PRESSURE REGULATING VALVE PER AMM 36-11-01/03. LEAK CHECKED PER TASK 36-11-01-790-801- / A/500. CHECK GOOD. THIS SDR IS FOR THE NACELLE PRESSURE REGULATING VALVE ON ENGINE NR 2. (SEE CONTROL AALA201810179001 AND AALA201810179002)