LGT HAS TAIL STRIKE ON LNDG BUT UNAWARE.

Narrative

OUR FLT WAS ON VECTORS FROM AN LDA APCH TO RWY 18 AT DCA ARPT. DURING THE FINAL PORTION OF OUR DSCNT WE WERE IN A TAILWIND CONDITION AND FASTER THAN NORMAL AIRSPDS WERE ASSIGNED BY ATC. THEREFORE; AFTER CLRNC FOR THE APCH WAS GIVEN; I FOUND MYSELF A LITTLE HIGHER THAN AN IDEAL PROFILE WOULD BE. I CONFIGURED THE ACFT WITH GEAR; FLAPS AND SPD BRAKES TO GET A GREATER DSCNT RATE. WHEN WE BROKE OUT AT 3000 FT AGL; I SAW THE RWY; THE RWY ENVIRONMENT AND ANOTHER ACFT WAS ON FINAL. DUE TO THE PROX OF THE OTHER ACFT I WAS FORCED TO MAKE A CLRING TURN (S-TURN) TO GIVE HIM TIME TO CLR THE RWY. THIS APCH IS OFFSET AND REQUIRES A TURN TO LINE UP ON FINAL. WE WERE FULLY CONFIGURED AND FELT STABILIZED SO AFTER TURNING TO FINAL THE ACFT WAS LANDED IN THE FIRST 1000 FT WITH A SLIGHTLY FIRM TOUCHDOWN. NEITHER WE NOR; IT TURNED OUT AFTER QUESTIONING; THE FLT ATTENDANTS FELT ANYTHING ABNORMAL ABOUT THE LNDG. AFTER CLRING THE RWY; THE TWR ASKED US TO CALL THEM ON THE TELEPHONE. ANOTHER ACFT HAD RPTED SEEING SPARKS FROM THE REAR OF OUR ACFT. ALTHOUGH THE LGT IS SUSCEPTIBLE TO TAIL STRIKES; WE WERE VERY SURPRISED TO FIND A SLIGHT SCRAPE OF APPROX 8 INCHES BY 2 1/2 FT ON THE TAIL OF OUR ACFT. ANALYSIS OF THE FLT DATA RECORDER BY OUR COMPANY INDICATED THAT THE SPD BRAKES; WHICH WERE USED TO INCREASE OUR DSCNT RATE; HAD NOT BEEN STOWED PRIOR TO LNDG. IN THE HIGH WORKLOAD ENVIRONMENT OF THIS APCH; NEITHER THE CAPT NOR MYSELF HAD NOTICED THIS SIT; RESULTING IN A HIGHER THAN NORMAL PITCH ATTITUDE ON LNDG; AND THE SLIGHT TAIL SCRAPE. THE ACFT HAD NO INTERNAL DAMAGE; BUT WAS REMOVED FROM SVC FOR 1 DAY FOR TESTING AND TO REPLACE THE SCRAPED SKIN.