What was found
ON FLIGHT 3055, CREW REPORTED SMOKE DETECTED IN CABIN AND COCKPIT 30 SECONDS AFTER TAKEOFF. SMOKE WAS NOT VISIBLE. SMELLED LIKE PAPER, BREAD TOAST, AND RUBBER. AFTER ONE MINUTE WITH BOTH PACKS TURNED OFF WAS UNABLE TO RESET THEM. CREW DECLARED A EMERGENCY AND LANDED UNEVENTFULLY. FLIGHT ATTENDANT REPORTED ODOR CONTINUED UNTIL JUST PRIOR TO LANDING THEN DISSIPATED. AIRCRAFT REMOVED FROM SERVICE. REMOVED AND REPLACED ENVIRONMENTAL SLEEVE AT CONTROL UNIT IAW MM 21-51-02. OPERATION CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE.