Narrative:

On apr/sun/05; after departing ZZZZ; the purser called the captain to inform him there was an electrical smell in the first class cabin. The captain told the purser to check the lavatories and call back. The purser called back and said the smell was still in the cabin. The captain directed me to return to ZZZZ. He declared a mayday with departure and performed the red box; checklist and performance data. During the descent; the purser called back and said the smell had dissipated. After setting up the approach; the captain took the aircraft and performed an overweight landing at ZZZZ. The crash fire rescue equipment crews responded and terminated the emergency after landing. Passenger were deplaned uneventfully. Callback conversation with reporter revealed the following information: the reporter stated while the 'wet sock' smell was reported as strong in the cabin; there was no smell in the cockpit. The maintenance action taken is unknown; as a quick plane change was made and the crew received no report on maintenance findings. Callback conversation with reporter acn 653204 revealed the following information: maintenance checked the airplane after lng and found nothing. The reporter followed the aircraft history before and after the event and the only thing noted was an electrical hydraulic pump in the center hydraulic system had some problems. This pump was an input to the stabilizer trim system and maybe was overheating when the stabilizer was operated for landing and takeoff climb.

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Original NASA ASRS Text

Title: A B757-200 IN CLB AT 13000 FT DECLARED AN EMER AND DIVERTED DUE TO 'WET SOCK' SMELL IN CABIN. LANDED OVERWT. CAUSE UNKNOWN.

Narrative: ON APR/SUN/05; AFTER DEPARTING ZZZZ; THE PURSER CALLED THE CAPT TO INFORM HIM THERE WAS AN ELECTRICAL SMELL IN THE FIRST CLASS CABIN. THE CAPT TOLD THE PURSER TO CHK THE LAVATORIES AND CALL BACK. THE PURSER CALLED BACK AND SAID THE SMELL WAS STILL IN THE CABIN. THE CAPT DIRECTED ME TO RETURN TO ZZZZ. HE DECLARED A MAYDAY WITH DEP AND PERFORMED THE RED BOX; CHKLIST AND PERFORMANCE DATA. DURING THE DSCNT; THE PURSER CALLED BACK AND SAID THE SMELL HAD DISSIPATED. AFTER SETTING UP THE APCH; THE CAPT TOOK THE ACFT AND PERFORMED AN OVERWT LNDG AT ZZZZ. THE CFR CREWS RESPONDED AND TERMINATED THE EMER AFTER LNDG. PAX WERE DEPLANED UNEVENTFULLY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED WHILE THE 'WET SOCK' SMELL WAS RPTED AS STRONG IN THE CABIN; THERE WAS NO SMELL IN THE COCKPIT. THE MAINT ACTION TAKEN IS UNKNOWN; AS A QUICK PLANE CHANGE WAS MADE AND THE CREW RECEIVED NO RPT ON MAINT FINDINGS. CALLBACK CONVERSATION WITH RPTR ACN 653204 REVEALED THE FOLLOWING INFO: MAINT CHKED THE AIRPLANE AFTER LNG AND FOUND NOTHING. THE RPTR FOLLOWED THE ACFT HISTORY BEFORE AND AFTER THE EVENT AND THE ONLY THING NOTED WAS AN ELECTRICAL HYD PUMP IN THE CTR HYD SYS HAD SOME PROBS. THIS PUMP WAS AN INPUT TO THE STABILIZER TRIM SYS AND MAYBE WAS OVERHEATING WHEN THE STABILIZER WAS OPERATED FOR LNDG AND TKOF CLB.

Data retrieved from NASA's ASRS site as of January 2009 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.