A B747-100 CLBING THROUGH 14000 FT DECLARED AN EMER AND RETURNED TO DEP ARPT DUE TO SMOKE AND FUMES ACCOMPANIED WITH RUMBLING AND VIBRATIONS CAUSED BY FAILED #3 PACK AIR CYCLE MACHINE.

Narrative

CREW DEPARTED ZZZZ; FO; AFTER COMPLETION OF MAINT ON THE #1 PACK SYSTEM. WHILE CLBING THROUGH 14000 FT; THE CREW STARTED SMELLING SMOKE AND FUMES FOLLOWED BY UNUSUAL RUMBLING NOISE AND VIBRATIONS IN THE COCKPIT AREA. WHILE THE CAPT WAS AT THE CTLS; THE FO DECLARED AN IN FLT EMER REQUESTING IMMEDIATE DSCNT AND VECTORS BACK TO ZZZZ FOR ILS APCH. CREW REVIEWED ALL APPLICABLE EMER PROCS; INCLUDING REQUEST FOR CRASH FIRE RESCUE CREW STANDING BY FOR OUR UNEVENTFUL APCH AND LNDG. NO FURTHER PROBS. RECOMMEND A REVIEW OF APPLICABLE MAINT PROCS. SUPPLEMENTAL INFO FROM ACN 634581: THIS ACFT IS A PRIOR ACR Y ACFT WHERE ALL OF THE #2 PACKS HAVE BEEN REMOVED AND DEFERRED! TAKING INTO CONSIDERATION THE PRIOR MAINT; UNCERTAINTY OF SMOKE SOURCE AND PROXIMITY OF DEP ARPT; THE DECISION WAS MADE AND AGREED BY ALL CREW MEMBERS THAT AN IMMEDIATE RETURN TO ZZZZ; AT 711000 LBS WITHOUT DUMPING WAS THE MOST PRUDENT. CALLBACK CONVERSATION WITH RPTR ACN 635156 REVEALED THE FOLLOWING INFO: RPTR STATED THE SMOKE; FUMES; RUMBLING AND VIBRATION WAS CAUSED BY THE FAILURE OF THE #3 AIR CYCLE MACHINE. THE RPTR SAID WHEN IT FAILED; IT THREW PARTS DOWNSTREAM INTO THE WATER SEPARATOR; COOLING FAN AND CHECK VALVES. THE RPTR STATED THESE UNITS; AND A PACK TEMP CTLR; WERE REPLACED AND AN OVERWEIGHT LNDG INSPECTION WAS ACCOMPLISHED. THE RPTR SAID INBOUND TO THIS STATION ON THE OVERNIGHT LAYOVER; THE #1 PACK HAD PROBS AND SOME TEMP SENSORS WERE REPLACED. CALLBACK CONVERSATION WITH RPTR ACN 634581 REVEALED THE FOLLOWING INFO: THE RPTR STATED THE CREW NOTED A METALLIC SMELL AND TASTE COMING FROM THE VENT ABOVE THE GLARE SHIELD. THE RPTR SAID THIS WAS FOLLOWED BY A LOUD BANG AND VIBRATION. THE RPTR STATED AN EMER WAS DECLARED AND A DSCNT STARTED AND BOTH PACKS SHUT DOWN. THE RPTR SAID AN OVERWEIGHT LNDG WAS MADE. THE RPTR STATED THE #3 PACK AIR CYCLE MACHINE HAD FAILED AND DAMAGED DOWNSTREAM COMPONENTS.