A319 ON APCH TO LAS; EXPERIENCED FLAP OVERSPEED ON APCH; CITING MULTIPLE RWY CHANGES AND MCDU PROBLEMS ON APCH AS CONTRIBUTING FACTORS.

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WE WERE ON THE SUNSET 2 ARR INTO LAS AND HAD BEEN TOLD TO EXPECT A VISUAL APCH TO RWY 25L. AS WE APCHED A POINT ABOUT 12-15 MI W OF THE ARPT THE CTLR TOLD US TO TURN TO A HDG OF 070 DEGS FOR A VECTOR TO A VISUAL APCH TO RWY 7R. HE DSNDED US TO 8000 FT AND HAD US SLOW TO 210 KTS. THIS SPD REDUCTION WHILE TRYING TO DSND CAUSED US TO BE WAY ABOVE PROFILE. THEN HE CLRED US TO 6000 FT. AS WE FLEW CLOSER TO THE ARPT; I'M GUESSING 8-9 MI HE SAID 'ACR X CHANGE OF PLAN. NOW YOU ARE CLRED VISUAL APCH TO RWY 19L. DO NOT DSND BELOW 4500 FT UNTIL 6 MI W; THEN TURN FINAL ABEAM THE STRATOSPHERE TWR AT 3500 FT.' I TOLD HIM WE COULDN'T POSSIBLY DSND THAT STEEPLY; SLOW DOWN; AND FLY THE APCH; SO HE TOLD US DEVS TO THE N WERE APPROVED. AS ALL THIS WAS HAPPENING WE HAD TO CHANGE THE LNDG RWY IN THE MCDU 3 TIMES (RWYS 25L; 7R; AND 19L). THE FO WAS VERY BUSY WITH THE RADIOS AND TELLING THE CTLRS THAT THE PATH THEY PUT US ON WAS TOO STEEP. DUE TO THE RAPIDLY COMPRESSING TIME FACTOR; I BEGAN TO MAKE THE NEEDED ENTRIES IN THE CAPT SIDE MCDU. AFTER CLRING THE UNNEEDED POINTS; I KEPT PUNCHING BUTTONS TO BRING UP THE APCH PAGE AND TO ACTIVATE AND CONFIRM. THE PROB WAS AT SOME POINT IN THE RAPID ENTRY OF DATA; MY MCDU LOCKED UP AND APPARENTLY DID NOT TAKE THE ACTIVATE/CONFIRM COMMAND. MY ATTN WAS BY NECESSITY DRAWN BACK OUTSIDE TO RESOLVE THE FLT PATH AND DSCNT PROB AS WELL AS CALLING FOR GEAR AND FLAPS; ETC. AFTER I CALLED FOR FLAPS FULL; I NOTICED THE MCDU HAD LOCKED UP AND ASKED THE FO TO CLR THE UNNEEDED POINTS AGAIN. NEITHER OF US NOTICE THAT THE MCDU HAD NOT ACCEPTED MY ACTIVATE/CONFIRM COMMAND. I WAS DSNDING WITH FLAPS FULL AND GEAR DOWN APCHING ABOUT 4000 FT; BUT STILL A BIT HIGH. WHEN I PUSHED THE SPD BUTTON IN; THE PWR CAME UP; DRIVING THE SPD ABOUT 3-5 KTS ABOVE MAX FLAP SPD FOR SEVERAL SECONDS WHILE I PULLED THE NOSE UP AND REDUCED THE SPD AND GOT THE ENGS TO SPOOL BACK DOWN TO IDLE. I REALIZED WHAT HAD HAPPENED TRIED AGAIN TO ACTIVATE AND CONFIRM; BUT MY MCDU WAS STILL LOCKED UP. I ASKED THE FO TO DO IT ON HIS MCDU WHICH WORKED. HE ALSO HAD TO CLR OUT THE LAST REMAINING POINT; PPOS. AFTER LNDG I WROTE UP THE FLAP OVERSPD AND ASKED MAINT TO COME LOOK AT THE PLANE. THE MECHS DID THE REQUIRED CHKS AND FOUND NO DAMAGE HAD BEEN DONE. THIS STARTED OUT AS A VERY ROUTINE ARR INTO LAS. THERE WERE A NUMBER OF FACTORS WHICH LED TO THE PROB. THESE WERE: ATC ISSUED SEVERAL RWY CHANGES IN A VERY SHORT PERIOD OF TIME. THIS WAS COMPLICATED BY BEING VERY CLOSE TO THE ARPT AND VERY HIGH WHEN THE CTLR GAVE US THE VISUAL APCH TO RWY 19L. ATC KEPT US HIGH FOR A LONG TIME. IT WOULDN'T HAVE BEEN ANY PROB FOR RWY 25L OR 7R; BUT IT WAS VERY STEEP FOR RWY 19L FROM OUR POS WHEN CLRED. HAD TO CLR WAYPOINTS SEVERAL TIMES. MY MCDU LOCKED UP; PROBABLY BECAUSE OF THE RAPID SUCCESSION OF ENTRIES I MADE. I WENT FROM CLRING WAYPOINTS AND PPOS TO CHANGING PAGES AND HITTING ACTIVATE AND CONFIRM IN VERY QUICK SUCCESSION. DUE TO THE NEED TO LOOK OUTSIDE TO PLACE THE ACFT ON THE PROPER SLOPE AND GND TRACK WHILE SIMULTANEOUSLY CHANGING THE CONFIGN AND SPD; I NEVER CHKED TO ENSURE ALL MY MCDU ENTRIES HAD BEEN ACCEPTED. I DIDN'T NOTICE THE MCDU LOCK UP UNTIL AFTER I PRESSED IN THE SPD BUTTON AND THE ENG SPOOLED UP DRIVING THE SPD ABOVE THE MAX. I ESSENTIALLY ALLOWED THE CTLR TO TAKE CTL OF MY PLANE BY GIVING THE BELATED RAPID SUCCESSION OF CTL INSTRUCTIONS. I SHOULD HAVE JUST SAID 'UNABLE' AND LET THE CTLR FIGURE OUT WHAT TO DO INSTEAD OF ME TRYING TO SAVE AN APCH WHICH WAS GIVEN TOO LATE; TOO CLOSE IN; AND TOO HIGH. IF THE MCDU HADN'T LOCKED AND EVEN IF I WOULD HAVE SEEN THAT IT HAD LOCKED AND THE PPOS AND ACTIVE/CONFIRM HAD NOT BEEN ACCEPTED; I COULD HAVE FLOWN THE APCH WITHOUT EXCEEDING THE FLAP SPD. ONE OF THE BIGGEST FACTORS WHICH LED ME TO NOT DECLINE SUCH A CLOSE IN 'ATC SLAM DUNK' WAS THAT I WAS CONCERNED WITH THE NEED TO SAVE FUEL DUE TO THE RUNAWAY FUEL PRICES. IN THE FUTURE; IF A CTLR GIVES ME A CLRNC TO DO SOMETHING THAT APCHS THE LIMITS OF THE PLANE OR MYSELF AS THE PLT;I WILL SIMPLY SAY 'UNABLE' AND FORCE THE CTLR SET THINGS UP BETTER.