RWY EXCURSION AFTER LNDG. AERONCA CHAMP RUNS INTO DITCH; ACFT DAMAGED.

Narrative

IN L CLOSED TFC (RWY 4L) FOR TOUCH-AND-GOES. 3 LNDGS HAD BEEN COMPLETED. TFC SEEMED HVY SO I DECIDED TO LAND (#4); TAXI BACK; AND DEPART TO THE NE. AFTER LNDG I WAS TAXIING DOWN RWY 4L TOWARDS THE MIDFIELD TXWY. UPON BRAKING (TO FURTHER SLOW DOWN FOR THE L TURN ONTO THE TXWY); I NOTICED THAT ONLY THE L BRAKE MUST HAVE BEEN EFFECTIVE; BECAUSE THE AIRPLANE VEERED SLIGHTLY TO THE L. I TRIED TO COMPENSATE BY GIVING IT R RUDDER; THEN FULL R BRAKE -- NOTHING HAPPENED. THERE WAS NO R BRAKE. BY THIS TIME THE AIRPLANE HAD LEFT THE RWY ONTO THE DIRT. (I COULDN'T HAVE BEEN GOING MORE THAN 5-10 MPH.) THERE SEEMED TO BE LOTS OF ROOM IN THE DIRT SO I THOUGHT I'D LET THE AIRPLANE ROLL TO A STOP BY ITSELF; ALL THE TIME TURNING TO THE L. I WAS REALLY PUSHING ON THE R BRAKE; STILL NOTHING HAPPENED. I SAW THE DITCH (1 1/2 - 2 FT DEEP) ABOUT 2 OR 3 SECONDS BEFORE IMPACT. THE R MAIN GEAR DROPPED IN AND THE PROP HIT THE DIRT. I IMMEDIATELY SHUT OFF THE FUEL AND ALL ELECTRICAL; THEN EXITED. NO INJURIES TO ME. AIRPLANE R MAIN WAS BENT BACK. PROP WAS RUINED AND THE L MAIN LOOKED A LITTLE BENT. R WINGTIP HAD A LITTLE SCRAPE ON THE UNDERSIDE. IF I HAD SEEN THE SMALL DITCH I MAY HAVE BEEN ABLE TO INTENTIONALLY GND LOOP IT TO THE L.