What was found
BOTH PRESSURE CONTROLLERS FAILED. DESCENDED TO FL180. OPERATED NORMALLY IN MAN MODE. *S/D* 3/27/01 AT LHR, AUTO PRESS SYSTEM NR 2 WAS DEFERRED INOP. ACFT FLEW TO ORD WITH NO PRESSURIZATION FAULTS. DURING ORD-IAD LEG, FLIGHT CREW REPORTED FAILURE OF BOTH AUTO CABIN PRESSURE CONTROLLERS. REPLACED NR 2 AC MOTOR. 3/29/01: DF534 WAS CREATED FOR AUTO PRESS SYSTEM NR 2. BITE ON BOTH NR 1 & 2 CPC SHOWED NR 2 AC MOTOR FAULT. 4/5/01: REPLACED NR 2 AC MOTOR (MR21324-142 OFF, -80 ON). ENGINEERING CALLOUT (EG3456) ACCOMPLISHED ON 4/18/01, PERFORMED WIRE CHECKS BETWEEN AC MOTORS AND CABIN PRESS CONTROLLERS. NO DISCREPANCIES WERE FOUND.