Narrative:

We pushed back from the gate in bos and completed the before start checklist. We then started the #2 engine which started normally. When the pushback was complete, we set the parking brake and the ground crew disconnected the tow bar. Once they were clear, we started the #1 engine. The start was normal but prior to beginning the after start flows and checklist, we smelled smoke in the cockpit. The flight attendant contacted us and noticed the smell in the cabin. A thin haze became visible. I immediately shut down both engines and waited a moment to see if the smoke would clear. It did, so we contacted operations and had them tow us back to the gate. No emergency was declared and we did not evacuate/evacuation the aircraft. The first officer thought the smell was from burning electrical equipment. I couldn't distinguish the odor and maintenance found no malfunction. I was concerned that exhaust may have been directed into the cabin by the packs, but they were selected off per the before start checklist. I looked up at the overhead panel after the engines were shut down and they were selected off so I don't know what the cause may have been. As a precaution, we shut down and returned to the gate.

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Original NASA ASRS Text

Title: A D328 CREW, WHILE PUSHING BACK AFTER ENG START AT BOS, EXPERIENCED SMOKE IN THE CABIN AND COCKPIT.

Narrative: WE PUSHED BACK FROM THE GATE IN BOS AND COMPLETED THE BEFORE START CHKLIST. WE THEN STARTED THE #2 ENG WHICH STARTED NORMALLY. WHEN THE PUSHBACK WAS COMPLETE, WE SET THE PARKING BRAKE AND THE GND CREW DISCONNECTED THE TOW BAR. ONCE THEY WERE CLR, WE STARTED THE #1 ENG. THE START WAS NORMAL BUT PRIOR TO BEGINNING THE AFTER START FLOWS AND CHKLIST, WE SMELLED SMOKE IN THE COCKPIT. THE FLT ATTENDANT CONTACTED US AND NOTICED THE SMELL IN THE CABIN. A THIN HAZE BECAME VISIBLE. I IMMEDIATELY SHUT DOWN BOTH ENGS AND WAITED A MOMENT TO SEE IF THE SMOKE WOULD CLR. IT DID, SO WE CONTACTED OPS AND HAD THEM TOW US BACK TO THE GATE. NO EMER WAS DECLARED AND WE DID NOT EVAC THE ACFT. THE FO THOUGHT THE SMELL WAS FROM BURNING ELECTRICAL EQUIP. I COULDN'T DISTINGUISH THE ODOR AND MAINT FOUND NO MALFUNCTION. I WAS CONCERNED THAT EXHAUST MAY HAVE BEEN DIRECTED INTO THE CABIN BY THE PACKS, BUT THEY WERE SELECTED OFF PER THE BEFORE START CHKLIST. I LOOKED UP AT THE OVERHEAD PANEL AFTER THE ENGS WERE SHUT DOWN AND THEY WERE SELECTED OFF SO I DON'T KNOW WHAT THE CAUSE MAY HAVE BEEN. AS A PRECAUTION, WE SHUT DOWN AND RETURNED TO THE GATE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.