Narrative:

On takeoff; both the first officer and I noticed a smell similar to burning plastic in the cockpit. There was no smoke in the cockpit. As we climbed out of 5;000 feet; the flight attendants called and reported a strong smell of something burning and that the passengers were reporting the same smell to them.I transferred control of the aircraft to the first officer as I spoke with the flight attendants. We determined that the best course of action was to return to the airport. We requested to level off at 9;000 feet and advised ATC. I began the smoke and fumes checklist as we entered a downwind vector to return to the field. We descended and executed the runway xx ILS approach to an overweight landing of approximately 163;000 pounds. Upon exiting the runway; we requested an inspection by crash fire rescue personnel who met the aircraft. They reported a normal heat signature on the aircraft. We returned to the terminal and parked at gate. We were met by station maintenance personnel to discuss the incident; and then wrote up the details for the smoke/fumes incident and the overweight landing in the aml.we loaded our passengers onto a new aircraft and departed approximately 2 hours late.I suspect that this event may have been the result of a recent engine change. Maintenance told us upon our return that there had been an engine change. Possibly some residual fluid that entered the bleed air system upon takeoff and climb at high power.I do not have any suggestions for avoiding a recurrence of this event I believe the situation was handled appropriately by both the cabin and flight deck crew when one considers the very real possibility of a potential fire.

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Original NASA ASRS Text

Title: B737 Captain reported that smoke and fumes in the cabin resulted in a return to land.

Narrative: On takeoff; both the First Officer and I noticed a smell similar to burning plastic in the cockpit. There was no smoke in the cockpit. As we climbed out of 5;000 feet; the flight attendants called and reported a strong smell of something burning and that the passengers were reporting the same smell to them.I transferred control of the aircraft to the First Officer as I spoke with the flight attendants. We determined that the best course of action was to return to the airport. We requested to level off at 9;000 feet and advised ATC. I began the smoke and fumes checklist as we entered a downwind vector to return to the field. We descended and executed the Runway XX ILS approach to an overweight landing of approximately 163;000 pounds. Upon exiting the runway; we requested an inspection by crash fire rescue personnel who met the aircraft. They reported a normal heat signature on the aircraft. We returned to the terminal and parked at gate. We were met by station Maintenance Personnel to discuss the incident; and then wrote up the details for the smoke/fumes incident and the overweight landing in the AML.We loaded our passengers onto a new aircraft and departed approximately 2 hours late.I suspect that this event may have been the result of a recent engine change. Maintenance told us upon our return that there had been an engine change. Possibly some residual fluid that entered the bleed air system upon takeoff and climb at high power.I do not have any suggestions for avoiding a recurrence of this event I believe the situation was handled appropriately by both the cabin and flight deck crew when one considers the very real possibility of a potential fire.

Data retrieved from NASA's ASRS site 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.