A DC9-30 FLYING IN ZID AIRSPACE; SUFFERS A PARTIAL ELECTRICAL FAILURE WITH NO INDICATIONS OF PWR LOSS. EMER IS DECLARED BECAUSE THE CAPT LOSES MOST OF HIS FLT INSTS.

Narrative

AFTER LEVELOFF AT FL350 WE STARTED TO GET SEVERAL UNRELATED SYS FAILURES. CIRCUIT BREAKERS STARTED POPPING AND AFTER 2-3 MINS THE L SIDE OF THE ACFT LOST MOST OF ITS ELECTRICAL PWR. LOST THE CAPT'S VOR AND RADIO AND SOON THEREAFTER; THE ATTITUDE INDICATOR. THE ELECTRICAL ABNORMALITIES CHKLIST WAS RAN BUT NO SYS FAILURES WERE INDICATED. WE DEDUCED WE HAD A PROB WITH THE L AC BUS BUT HAD NO 'BUS' FAILURE LIGHTS AND THE BUS DID NOT AUTO SWITCH TO THE R SIDE AS IT SHOULD HAVE. IT WAS VFR AND WE RETURNED TO DTW UNEVENTFULLY. IT MAY HAVE BEEN A DIFFERENT CASE HAD IT BEEN IFR. THE DC9 IS GETTING OLD AND ELECTRICAL FAILURES ARE MORE COMMON. WHAT IS DISTURBING IS THE WARNING AND AUTO SWITCHING SYS ARE NOT WORKING AS THEY SHOULD. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT THE FLT INSTS ON THE CAPT'S SIDE BEGAN TO FAIL WITHOUT INDICATIONS OF ANY ELECTRICAL PWR LOSS; SUCH AS THE XFER BUS ILLUMINATING OR ANY OTHER RED LIGHTS. WHEN THE DECISION WAS MADE TO RETURN TO POINT OF DEP; AN EMER WAS DECLARED. ONLY INSTS ON THE R SIDE KEPT WORKING. THERE WAS ONLY 1 CIRCUIT BREAKER THAT HAD TRIPPED; WHICH WAS A CIRCUIT BREAKER FOR A SINGLE PHASE OF A 3 PHASE GENERATOR. AFTER THE ACFT LANDED AND TAXIED TO THE GATE AND PARKED; AS THE ENGS WERE BEING SHUT DOWN; MANY OTHER CIRCUIT BREAKERS TRIPPED TO THE OPEN POS. THE ACFT WAS A DC9-30; AND THE FAULT WAS ONLY 1 SINGLE PHASE CIRCUIT BREAKER THAT HAD FAILED. NO OTHER FAULT LIGHT OR BUS XFER LIGHTS ILLUMINATED. NO AUTO XFER OF ELECTRICAL PWR OCCURRED. THERE WAS NO WARNING AS IT WAS A PARTIAL FAILURE; EVEN THOUGH MOST INSTS ON THE L SIDE HAD FAILED. THE L AC BUS FAILED; BUT ONLY 1 PHASE CIRCUIT BREAKER FAILED. WHEN THAT CIRCUIT BREAKER WAS REPLACED; THE ACFT OPERATED NORMALLY.