A B767-200 IN CRUISE AT FL350 EXECUTED AN EMER DSCNT DUE TO LOSS OF CABIN PRESSURE CTL. REGAINED MANUAL CTL AT 10000 FT. CAUSED BY FAILED OUTFLOW VALVE AC MOTOR.

Narrative

CLBING FROM FL 330 TO FL 350 RECEIVED A CABIN ALT WARNING LIGHT HORN. CABIN ALT WAS ABOVE 10000 FT AND CLBING 300/400 FPM. WE RECEIVED CLRNC AND INITIATED AND EXPEDITED DSCNT TO 10000 FT. DURING THE DSCNT WE DETERMINED THAT BOTH OF OUR 2 AUTOPRESSURIZATION CTLRS FAILED. THE HIGHEST CABIN ALT ATTAINED WAS 12500 FT. AT 10000 FT WE REESTABLISHED CTL OVER OUR PRESSURIZATION SYS WITH OUR BACKUP MANUAL PRESSURIZATION CTLR. AFTER CONSULTATION WITH OUR DISPATCHES AND MAINT COORDINATORS AND AFTER DETERMINING THAT OUR PAX WERE IN NO PHYSICAL DISTRESS; WE CLBED BACK TO 22000 FT AND RESUMED OUR FLT TO DEN FOR AN UNEVENTFUL APCH AND LNDG. WE DONNED OUR OXYGEN MASKS IN THE COCKPIT WHEN BROUGHT BACK BELOW 10000 FT SO QUICKLY THAT OUR OXYGEN PAX MASKS DID NOT DEPLOY. ALL EMER AND ABNORMAL CHKLIST WERE COMPLETED. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CAUSE OF THE CABIN ALT TO CLB AND THE FAILURE OF THE SYS TO SWITCH TO AN OPERATIVE OUTFLOW WAS TWO SEPARATE PROBLEMS. THE RPTR SAID THE #2 OUTFLOW VALVE AC MOTOR HAD FAILED IN ADDITION THE AUTOPRESSURE CTLR SWITCHING AND ALERTING CIRCUIT FAILED THEREFORE NO SWITCHING OCCURRED.