A DC9 EXPERIENCED RAPID DEPRESSURIZATION AND AN ACFT 90 DEG BANK SIMULTANEOUSLY. THE CREW DECLARED AN EMER AND DSNDED.

Narrative

DURING DSCNT FROM FL320 TO 16000 FT; PRESSURIZATION SET FOR LNDG AT ZZZ; CABIN PRESSURE WARNING CAME ON AND AT SAME TIME; AUTOPLT WENT INTO A 90 DEG BANK. THIS OCCURRED BTWN FL270-FL260. PRIOR TO THIS; DSCNT WAS NORMAL AT 2500 FPM AND 1-2 EPR. OUTSIDE AIR TEMP AT FL320 WAS -12 DEGS CELSIUS. IN AND OUT THE TOPS NO ICE ON ACFT. DISCONNECTED AUTOPLT AND USED MANUAL PRESSURIZATION TO RECOVER CABIN AND ACFT. WENT ON OXYGEN DURING RECOVERY OF CABIN. ONCE MANUAL PRESSURIZATION RECOVERED; THE CABIN AND WARNINGS OUT. AUTOPLT WORKED NORMALLY FOR REST OF THE FLT. MAX AIRSPD DURING DSCNT NEVER WENT OVER 310 KTS. BUT THERE WAS A SHUDDER DURING PRESSURE LOSS AND ROLL. UPON LNDG AT ZZZ; WALK AROUND ACFT FOUND NO DAMAGE. AFTER TALKING TO MAINT AND REVIEWING ACFT HISTORY OF AUTO PRESSURIZATION PROB. DEFERRAL OF AUTO PRESSURIZATION WAS DONE. AUTOPLT WORKED ON LEG FROM ZZZ-ZZZ1 USING MANUAL PRESSURIZATION. EARLY IN THE FLT; THE RED IU IN THE MFD CAME ON. PERFORMED ABNORMAL AND WARNING WENT AWAY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE COMPANY MECHS SUSPECTED AN ELECTRICAL WIRING FAULT; BUT DID NOT PINPOINT THE EXACT CAUSE. THE RPTR HAS BEEN UNABLE TO TALK WITH ANYONE ABOUT A FINAL RESOLUTION.