MD80 FLC EXPERIENCED SMOKE DURING ENG START; SHORTLY AFTER PUSHBACK. PROCS FOR AIR-CONDITIONING PACK MALFUNCTION; SMOKE REMOVAL WERE FOLLOWED; AND #1 ENG SHUT DOWN; AND STILL NO SOLUTION. MAINT FOLLOW-UP DISCOVERED APU FAILURE.

Narrative

DURING PUSHBACK AND JUST AFTER THE L ENG WAS STARTED SMOKE BEGAN COMING INTO THE MAIN CABIN AND COCKPIT THROUGH THE AIR-CONDITIONING SYS. THE FO RPTED THAT HE DID NOT THINK THE R AIR-CONDITIONING PACK FAN HAD COME BACK ON AND THAT THE R PACK MIGHT BE GETTING HOT SO WE TURNED THE R AIR-CONDITIONING PACK OFF. THE SMOKE SEEMED TO DISSIPATE FOR A FEW SECONDS. THEN THE GND MAN ON THE HEADSET RPTED SEEING A BRIEF FLASH AND SOME SMOKE NEAR THE L ENG AND THE FLT ATTENDANTS SIMULTANEOUSLY RPTED THAT THE SMOKE IN THE CABIN WAS INCREASING. THERE WERE NO FIRE INDICATIONS AND THE L ENG WAS RUNNING NORMALLY; HOWEVER; I SHUT IT DOWN AND WE BEGAN THE SMOKE REMOVAL CHKLIST. WITH ALL AIR-CONDITIONING PACKS OFF AND ALL BLEED AIR SOURCES TURNED OFF THE SMOKE BEGAN TO DECREASE. AS A PRECAUTION I DIRECTED THE FO TO CALL GND CTL AND HAVE THE CFR TRUCKS COME TO THE ACFT AND STANDBY. AT THIS POINT WE HAD ONLY THE APU RUNNING FOR ELECTRICITY AND NO VENTILATION CAPABILITY. WHILE THE SMOKE WAS DISSIPATING; IT WAS STILL ACRID. I THEN DIRECTED THE FLT ATTENDANTS TO DISARM THE FORWARD ENTRY AND AFT GALLEY SLIDES AND OPEN THOSE 2 DOORS TO VENTILATE THE ACFT. WE ALSO BEGAN PREPARATIONS TO BE TOWED BACK TO THE GATE. AFTER THE MAIN CABIN SMOKE CLRED SOMEWHAT WE CLOSED THE 2 OPEN DOORS AND BEGAN TOWING TO THE GATE. A FEW SECONDS BEFORE REACHING THE GATE THE APU FAILED OR AUTO SHUT DOWN. UPON REACHING THE GATE ALL PAX WERE IMMEDIATELY DEPLANED THROUGH THE FORWARD ENTRY DOOR INTO THE TERMINAL. 1 PAX RPTED BEING CHEMICALLY SENSITIVE BUT SUBSEQUENT INVESTIGATION REVEALED APU FAILURE.