A B737-200 ON FINAL APCH AT 800 FT HEARD A THUMP AND PF REQUIRED 20 DEGS OF R AILERON INPUT TO CORRECT FOR L ROLL; WHICH WAS LATER DETERMINED TO BE A SPINDLE FAILURE.

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ON ARR; WE WERE CLRED VISUAL APCH. ACFT WAS SLOWED NORMALLY AND FLAPS EXTENDED TO 5 DEGS. GEAR WAS EXTENDED AND FLAPS EXTENDED TO 15 DEGS. AT APPROX 1100-1200 FT; TWR ADVISED US THAT A T38 WAS ON CLOSE IN R BASE TO OUR RWY AND WOULD EXTEND TO FOLLOW US. ALMOST SIMULTANEOUSLY; WE RECEIVED A TCASII TA. WE BOTH BEGAN LOOKING FOR THE T38. HE WAS SIGHTED AT 1 O'CLOCK POS. NO FACTOR. BY THIS TIME; WE HAD PASSED THROUGH 1000 FT. FLAPS WERE EXTENDED TO 30 DEGS AND BEFORE LNDG ACCOMPLISHED. NORMAL CALLOUTS WERE MADE. AT APPROX 300-400 FT; WE HEARD A THUMP WHICH SOUNDED EXACTLY LIKE A BIRD STRIKE. WE CONTINUED THE APCH. THE AIR WAS QUITE CHOPPY AS IS USUAL FOR AFTERNOON SUMMER DAYS. ON VERY SHORT FINAL; I NOTICED THAT THE FO WAS HAVING TO HOLD APPROX 20 DEGS OF R AILERON (AVERAGE; WHILE CONTENDING WITH THE BUMPS). BY THIS TIME; WE WERE IN THE FLARE AND MADE A NORMAL TOUCHDOWN. TAXIING IN; I ASKED THE FO IF HE FELT THAT HE WAS HAVING TO COUNTERACT A L ROLL TENDENCY AND HE AGREED THAT HE WAS. WE DECIDED TO LEAVE THE FLAPS EXTENDED AND HAVE THE SPINDLES CHKED; ALSO TO CHK FOR A BIRD STRIKE. I CALLED THE DISPATCHER FOR A PATCH TO THE DESK IN MAINT. I TOLD HIM THE WHOLE SCENARIO AND REQUESTED TO HAVE CONTRACT MAINT COME LOOK AT THE ACFT. HE AGREED AND WE CALLED THEM. WHILE WE WERE WAITING; I WENT OUT AND LOOKED AT THE FLAPS. WHEN I LIFTED UP ON THE TRAILING EDGE; IT WAS EVIDENT THAT THERE WAS A PROB; BECAUSE I COULD LIFT THE TRAILING EDGE OF THE L OUTBOARD FLAP PROBABLY 6 INCHES; BUT COULDN'T BUDGE THE R ONE. CONTRACT MAINT SHOWED UP AND HE AGREED THAT IT DIDN'T LOOK RIGHT TO HIM EITHER. HE CALLED THE MAINT DESK. THEY WERE IN THE PROCESS OF SENDING HIM A FAX CONCERNING A SPINDLE INSPECTION WHEN WE WERE ADVISED THAT A MECH WAS IN THE GATE AREA NON-REVVING. I ASKED HIM TO COME LOOK AT THE ACFT. HE DID AND IMMEDIATELY ADVISED US THAT THE SPINDLE WAS; IN FACT; BROKEN. THIS WAS OUR LAST LEG FOR THE DAY; SO WE WENT TO THE HOTEL AFTER I WAS SURE THAT THE ACFT WAS TO BE TAKEN OTS. I HAVE HAD MANY BIRD STRIKES IN MY CAREER AND HAD WE FOUND ANY EVIDENCE OF ANOTHER; WE MIGHT NOT HAVE HAD THE SPINDLE EXAMINED THINKING THAT THE THUMP WAS JUST ANOTHER UNLUCKY BIRD. THE REASON THAT I AM FILING THIS RPT IS DUE TO ONE; POSSIBLY TWO; PROCEDURAL DEVS. ONE WAS THE FACT THAT WE WERE DISTR BY THE TCASII ALERT AND FAILED TO BE CONFIGURED BY 1000 FT. TWO; WE DID NOT GO AROUND AFTER THE SPINDLE FAILURE. HAD THE 'THUMP' OCCURRED DURING FLAP EXTENSION; I WOULD HAVE SUSPECTED A FAILURE. HOWEVER; IT DID NOT; AND I DID NOT THINK ABOUT A POSSIBLE FAILURE UNTIL WE WERE ALMOST ON THE GND. I THINK THAT CONTINUING THE LNDG WAS THE BEST DECISION AT THAT STAGE OF THE FLT. I UNDERSTAND WHY THE SPINDLE FAILURE PROC WAS WRITTEN AND I AGREE WITH IT AND WOULD HAVE COMPLIED WITH IT HAD IT HAPPENED DURING FLAP EXTENSION (AS I WOULD HAVE SUSPECTED A FAILURE). SUPPLEMENTAL INFO FROM AN 620174: BY THE TIME I DECIDED THAT POP/BANG AND THE ABNORMAL CTL INPUTS MIGHT MEAN A SINGLE SPINDLE FAILURE; THE ACFT WAS NEARLY IN THE FLARE. THE CAPT HAD HEARD THE POP/BANG; BUT THE CTL INPUTS I HAD BEEN USING FOR THE VARIABLE WINDS MADE IT HARD FOR HIM TO DETECT THE ACFT FLYING ABNORMALLY. I LET MYSELF GET DISTR BY 2 ACFT AND NUMEROUS BIRDS. WITH THE FOCUS OF CTLING THE ACFT IN GUSTY WINDS ON SHORT FINAL AND NEVER HAVING EXPERIENCED A SPINDLE FAILURE; I WAS SLOW TO REALIZE THE ACTUAL PROB. THE PROB IS WHAT TO COMMUNICATE WHEN ON SHORT FINAL; AND THE PERSON WHO SHOULD BE FOCUSING ON CTLING THE ACFT IS TRYING TO DECIDE WHAT THE PROB IS.