A B737 IN CLB AT 3000 FT DECLARED AN EMER AND DIVERTED DUE TO AN AIRFRAME VIBRATION AND OIL SMELL CAUSED BY A FAILED L PACK FLOW CTL VALVE DUCTING.

Narrative

DURING THE CLBOUT FROM TPA THE CREW EXPERIENCED A SUDDEN AND CONTINUOUS LOUD RUMBLE AND VIBRATION. THE VIBRATION WAS SEVERE ENOUGH TO CONCLUDE THAT THE ENTIRE AIRFRAME WAS SHAKING. WE REDUCED OUR CLB RATE AND REDUCED ENG CLB PWR. WHILE WE WERE TRYING TO DETERMINE THE CAUSE OF THE VIBRATION; THE LEAD FLT ATTENDANT CALLED THE COCKPIT ON THE INTERPHONE; INFORMING US OF THE AIRFRAME VIBRATION; THE NOISE; A 'HVY OILY SMELL;' AND A CABIN TEMP INCREASE. AFTER HEARING THIS INFO FROM THE CABIN; WE DECIDED TO RETURN TO TPA ASAP. WE INFORMED ATC OF OUR SIT; AND TO BE SAFE; TOLD THEM TO 'ROLL THE TRUCKS.' WITH THE HVY OILY SMELL; WE ALSO DECLARED AN EMER. A PA ANNOUNCEMENT WAS MADE INFORMING THE PAX OF OUR RETURN TO TPA. THE FLT ATTENDANTS TOLD US EVERYTHING WAS NORMAL -- NO MORE OILY SMELL AND EVERYONE WAS SEATED WITH SEAT BELTS FASTENED. THE LEAD FIRE/RESCUE PERSONNEL ALSO STATED EVERYTHING LOOKING NORMAL ABOUT THE ACFT EXTERIOR. MECHS INSPECTED ALL WING AND NOSE CONE SURFACES; LNDG GEAR AND DOORS; AIR CONDITIONING PACKS. THEY FOUND: 'L DOWNSTREAM FLOW CTL VALVE DUCT BLOWN.' REMOVED DUCT. REPLACED DUCT AND LEAK CHKED GOOD.