Narrative:

Climbing through 4000 ft flight attendant advised captain of strong burning smell in mid and aft cabin. While odor seemed to be dissipating, both mid and aft flight attendants feared the possibility of a fire/smoke situation with no obvious source. I returned to mci (origin) for precautionary landing. Declared emergency and requested equipment. Takeoff was from runway 09, a left 270 degree turn and descent put us right on runway 19L for uneventful landing. The burning odor was essentially gone by the time we landed. 6 mins flying time total. No smoke was ever seen, and source of fumes could not be determined. Decision to return was immediate. First officer flew aircraft and coordinated arrival while I remained on interphone with 1 flight attendant while the other searched for source of fumes. The possibility of aircraft evacuate/evacuation was briefly considered, but odds appeared low since fumes had been steadily decreasing and no source of smoke/fire/heat etc could be determined. No smoke identify/removal checklist was initiated since we were only 2 or 3 mins from landing when fumes were reported -- there simply wasn't time for such an involved procedure. Approach landing checklists were accomplished, and I was able to make a brief PA to reassure passenger, who were essentially unworried (smell was confined to mid and aft cabin, with no secondary indications such as smoke, sounds, etc to cause anxiety). Crew teamwork was excellent -- all crew members performed with the highest professionalism. Callback conversation with reporter revealed the following information: the reporter stated he was flying an MD88. Their flight was the first flight of the day after maintenance had done their normal overnight service. This could include service with fluids of the engines, hydraulics, and air cycle machine. Sometimes spillage of oils or hydraulics can find its way into the air conditioning ducting and cause fumes. Immediately on landing the maintenance checked the baggage compartments but nothing was found unusual. The WX was characterized as stormy and had been stormy all night. The crew and passenger were transferred to another aircraft and departed before determination was made as to the cause of the fumes.

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Original NASA ASRS Text

Title: FLT ATTENDANTS RPT FUMES FROM AN UNKNOWN SOURCE IN MID AND AFT CABIN. THE ACFT IS RETURNED FOR MAINT.

Narrative: CLBING THROUGH 4000 FT FLT ATTENDANT ADVISED CAPT OF STRONG BURNING SMELL IN MID AND AFT CABIN. WHILE ODOR SEEMED TO BE DISSIPATING, BOTH MID AND AFT FLT ATTENDANTS FEARED THE POSSIBILITY OF A FIRE/SMOKE SIT WITH NO OBVIOUS SOURCE. I RETURNED TO MCI (ORIGIN) FOR PRECAUTIONARY LNDG. DECLARED EMER AND REQUESTED EQUIP. TKOF WAS FROM RWY 09, A L 270 DEG TURN AND DSCNT PUT US RIGHT ON RWY 19L FOR UNEVENTFUL LNDG. THE BURNING ODOR WAS ESSENTIALLY GONE BY THE TIME WE LANDED. 6 MINS FLYING TIME TOTAL. NO SMOKE WAS EVER SEEN, AND SOURCE OF FUMES COULD NOT BE DETERMINED. DECISION TO RETURN WAS IMMEDIATE. FO FLEW ACFT AND COORDINATED ARR WHILE I REMAINED ON INTERPHONE WITH 1 FLT ATTENDANT WHILE THE OTHER SEARCHED FOR SOURCE OF FUMES. THE POSSIBILITY OF ACFT EVAC WAS BRIEFLY CONSIDERED, BUT ODDS APPEARED LOW SINCE FUMES HAD BEEN STEADILY DECREASING AND NO SOURCE OF SMOKE/FIRE/HEAT ETC COULD BE DETERMINED. NO SMOKE IDENT/REMOVAL CHKLIST WAS INITIATED SINCE WE WERE ONLY 2 OR 3 MINS FROM LNDG WHEN FUMES WERE RPTED -- THERE SIMPLY WASN'T TIME FOR SUCH AN INVOLVED PROC. APCH LNDG CHKLISTS WERE ACCOMPLISHED, AND I WAS ABLE TO MAKE A BRIEF PA TO REASSURE PAX, WHO WERE ESSENTIALLY UNWORRIED (SMELL WAS CONFINED TO MID AND AFT CABIN, WITH NO SECONDARY INDICATIONS SUCH AS SMOKE, SOUNDS, ETC TO CAUSE ANXIETY). CREW TEAMWORK WAS EXCELLENT -- ALL CREW MEMBERS PERFORMED WITH THE HIGHEST PROFESSIONALISM. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED HE WAS FLYING AN MD88. THEIR FLT WAS THE FIRST FLT OF THE DAY AFTER MAINT HAD DONE THEIR NORMAL OVERNIGHT SVC. THIS COULD INCLUDE SVC WITH FLUIDS OF THE ENGS, HYDS, AND AIR CYCLE MACHINE. SOMETIMES SPILLAGE OF OILS OR HYDS CAN FIND ITS WAY INTO THE AIR CONDITIONING DUCTING AND CAUSE FUMES. IMMEDIATELY ON LNDG THE MAINT CHKED THE BAGGAGE COMPARTMENTS BUT NOTHING WAS FOUND UNUSUAL. THE WX WAS CHARACTERIZED AS STORMY AND HAD BEEN STORMY ALL NIGHT. THE CREW AND PAX WERE TRANSFERRED TO ANOTHER ACFT AND DEPARTED BEFORE DETERMINATION WAS MADE AS TO THE CAUSE OF THE FUMES.

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.