MLG UNABLE TO PRESSURIZE RETURNS TO FIND E AND E DOOR NEVER CLOSED.

Narrative

NO PRESSURIZATION AFTER TKOF. ATTEMPTED STANDBY; MANUAL AC; MANUAL DC SYS TO NO AVAIL. INFORMED ATC AND LEVELED AT 3000 FT MSL. CHKED BREAKERS AND RAN APPROPRIATE CHKLISTS. NO DOOR WARNING LIGHTS DURING BEFORE START; TAXI; OR TKOF; EITHER ON OVERHEAD OR IN RECALL. RETURNED SFO; OVERWT LNDG. ADVISED MAINT OF OVERWT LNDG AND REASON FOR RETURN. MAINT FOUND OPEN ELECTRICAL COMPARTMENT DOOR. MAINT VERIFIED THAT DOOR WARNING SYS FOR THAT DOOR WAS INOP. MAINT HAD BEEN WORKING ON ACFT PRIOR TO DISPATCH AND RETURNED LOGBOOK TO CREW AFTER FLC WALKAROUND APPROX 5 MINS PRIOR TO DEP; WITH PROPER SIGNOFFS AND ACKNOWLEDGED THAT ACFT WAS ALL CLOSED UP AND READY TO GO. MAINT MEL'ED DOOR WARNING SYS FOR E/E DOOR AND PERFORMED AN OVERWT LNDG INSPECTION. PRIOR TO SECOND DEP; MAINT DISCOVERED BROKEN WIRE TO DOOR WARNING SWITCH IN E/E COMPARTMENT AND CORRECTED THE PROB. SUPPLEMENTAL INFO FROM ACN 252964: POSSIBLE SOLUTION: SINCE THE DOOR OPENS INWARD; IT IS IMPOSSIBLE TO SEE UNLESS YOU LOOK UNDER THE BELLY. IF A RED FLAG ATTACHED TO A WT WERE HUNG DOWN WHEN THE E/E DOOR WAS OPENED IT MIGHT PREVENT THIS DOOR FROM BEING LEFT OPEN.