What was found
CABIN ALTITUDE HIGH EICAS AT 330. ALL PAX MASKS DEPLOYED, NO AURAL INDICATION. CABIN ALTITUDE APPROXIMATELY 8800 AT 320. IN DESCENT, MASKS DEPLOY AUTO. DECLARED EMERGENCY, RETURNED TO FIELD, LANDED WITHOUT INCIDENT. FERRIED TO PIT. R&R MAU 2 GENERIC I/O SLOTS 9/10 IAW AMM 31-41-06. R&R POSITIVE PRESSURE RELIEF VALVE IAW AMM 21-32-01. R&R SPDA 1 DC POWER MODULE 13 IAW AMM 24-61-13. R&R CABIN ALTIMETER SWITCH IAW AMM 35-21-02. OFF PART # OFF PART DESCRIPTION OFF SERIAL # TSN (AS OF REMOVAL) CSN (AS OF REMOVAL) 1708011 DC POWER MODULE, SPDA 2457 32068.11 24725.00 7025365-1901 GENERIC I/O MODULE 10066817 2626.16 1918.00.