A B737-300 RT ENG VIB INCREASED DURING CLB OUT; SUBSEQUENT EGT RISE AND THE ENG BEGAN COMPRESSOR STALLS. AN EMER RETURN TO LAND WAS COMPLETED WHERE TURBINE DAMAGE WAS DISCOVERED.

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THIS IS THE DESCRIPTION OF WHAT HAPPENED ON ACFT X; ZZZ TO ZZZ1; JUL 08. THE PREFLT; TAXI AND TKOF WERE ALL UNEVENTFUL. I WAS THE PF AND THE CAPT WAS THE PNF. ON CLBOUT; PASSING ABOUT 7000 FT MSL THE CAPT AND I FELT A LOW VIBRATION COMING FROM THE AIRPLANE AND NOTICE AN INCREASE FROM NOTHING TO 2 ON THE #2 ENG'S VIBRATION GAUGE. ALL OTHER #2 ENG INSTS WERE NORMAL. WE CONTINUED TO CLB AND MONITOR THE #2 ENG WHILE THE CAPT BEGAN TO RESEARCH THE MAINT HISTORY FOR THE ACFT TO SEE IF THERE WERE ANY PREVIOUS WRITE-UPS ON THE #2 ENG. MEANWHILE; PASSING ABOUT FL180 WE NOTICED THE #2 ENG'S EGT RISING STEADILY FROM ABOUT 800; WHICH WAS EVEN WITH THE #1 ENG; TO AROUND 890. AT APPROX FL240 THE #2 ENG'S EGT REACHED 890 AND WE EXPERIENCED A LOUD BANG FOLLOWED BY 3 MORE SMALLER BANGS FROM THE R SIDE OF THE ACFT AND THE ACFT BEGAN TO SHUDDER. BOTH THE CAPT AND I RACED FOR THE AUTOTHROTTLE DISCONNECT BUTTONS; DISCONNECTING THE AUTOTHROTTLES; AND AT THAT TIME I RELINQUISHED CTL OF THE ACFT TO THE CAPT AS HE CALLED FOR THE ENG LIMIT/SURGE/STALL QRC. WE ACCOMPLISHED THE QRC AND ASSOCIATED CLEANUP ITEMS WHICH BROUGHT US TO BRING THE #2 ENG TO IDLE THRUST. EVEN THOUGH THE #2 ENG NEVER EXCEEDED ANY OPERATIONAL LIMITATIONS; DUE TO THE POSSIBLE DAMAGE FROM THE COMPRESSOR STALLS; WE ELECTED TO LEAVE IT AT IDLE THRUST FOR THE REMAINDER OF THE FLT. AT THAT TIME WE WERE APPROX 70 MI FROM ZZZ AND DECIDED TO DECLARE AN EMER AND TURN BACK TO ZZZ. WE CHKED THE ATIS WHICH FAVORED RWY 28 AT ZZZ WHICH WAS ALSO THE LONGEST CURRENT LNDG RWY. WE STATED OUR INTENTIONS TO ATC; INFORMED THE FLT ATTENDANTS OF A 'CABIN ADVISORY' ONLY; AND INFORMED THE PAX THAT WE WERE RETURNING TO ZZZ DUE TO AN ENG MALFUNCTION THAT WE HAD UNDER CTL. DURING THE DSCNT; WE HAD ENOUGH TIME TO GO BACK THROUGH ALL APPROPRIATE CHKLISTS FOR OUR ENG MALFUNCTION; CONTACT DISPATCH INFORMING THEM OF OUR SITUATION AND INTENTIONS; AND COMFORTABLY BRIEF THE APCH AND LNDG DATA FOR A SINGLE-ENG ILS/VISUAL APCH TO RWY 28 AT ZZZ. THE LNDG WAS UNEVENTFUL AND UPON TAXIING CLR OF RWY 28 WE ELECTED TO CANCEL THE FIRE/CRASH/RESCUE UNITS AND TAXI BACK TO PARKING. AFTER PARKING WE DEBRIEFED MAINT; DISPATCH; AND THE DUTY MGR ABOUT WHAT HAPPENED AND ACCOMPANIED AN ENG SPECIALIST TO OBSERVE THE DAMAGE TO THE #2 ENG; WHICH THERE WAS OBVIOUS DAMAGE AND MISSING TURBINE BLADES.