AIR TAXI ACFT HAS BRAKE FAILURE AFTER LNDG.

Narrative

I HAD ANTICIPATED AN ILS TO RWY 10 AT DPA; BUT THE APCH CTLR SAID TO EXPECT RWY 1L. RWY 1L TRUE COURSE BEING 015 DEGS; I NOW ANTICIPATED AN ACCEPTABLE XWIND LNDG. APCH AND LNDG WERE NORMAL; WITH ONLY SLIGHT DIRECTIONAL CTL ADJUSTMENTS MADE; WHICH I ATTRIBUTED TO XWIND. THE TWR CLRED ME TO THE FBO AND ACROSS RWY 10. I EXITED RWY 1L AT TXWY W8 (A L TURN); THEN TURNED R TO JOIN TXWY W NBOUND. I THEN MADE A L TURN ONTO TXWY G AND UPON JOINING TXWY G WBOUND; I NOTICED AN EXCEPTIONAL AMOUNT OF R RUDDER AND BRAKING WERE REQUIRED TO RE-CTR THE NOSEWHEEL. I HAD BEEN TAXIING AT ABOUT 3-5 KTS; CARRYING ABOUT 500 FPM EACH ENG. AS I PROCEEDED W ON G; MY TAXI SPD SEEMED TO ACCELERATE; AND I NOTED MY R BRAKE WASN'T RESPONDING. AT APPROX 50 FT FROM THE POINT TXWY G TURNS N TO CROSS RWY 10; I CLOSED BOTH THROTTLES. THE R BRAKE SEEMED INEFFECTIVE AND THE L WAS DOING LITTLE TO SLOW MY TAXI SPD. FULL R RUDDER AND HARD R BRAKE WAS APPLIED WITH NO DIRECTIONAL CHANGE. I QUICKLY THROTTLED UP THE L ENG; HOPING DIFFERENTIAL THRUST WOULD TURN THE ACFT. THIS ONLY INCREASED MY FORWARD SPD; BUT NO R TURN. I WAS NOW FULL R RUDDER; FULL R BRAKE; STANDING HARD ON THE L BRAKE; PULLING ON THE PARKING BRAKE ALL WITH BOTH THROTTLES CLOSED. IT WAS NOW APPARENT THE ACFT WAS NOT GOING TO MAKE THE TURN. AS THE NOSEWHEEL EXITED THE TXWY AND MADE INITIAL CONTACT WITH A SNOW/ICE BANK APPROX 14 INCHES IN HT; I PULLED THE MIXTURE CTLS TO IDLE CUTOFF. AS THE NOSEWHEEL CAME OVER AND DOWN THE SNOW BANK; THE NOSE GEAR COLLAPSED. THE ACFT STOPPED WITH THE MAIN TIRES STILL ON THE TXWY AND THE NOSE LYING IN ABOUT 3-4 INCHES OF SNOW OFF THE W SIDE. I REQUESTED ASSISTANCE FROM THE TWR AND SECURED THE ACFT. I INSPECTED THE ACFT EXTERIOR AND NOTED THE R BRAKE AND TIRE SOAKED WITH HYD OIL. THE NOSE GEAR HAD FOLDED AFT AND TO THE L; DAMAGING THE GEAR DOORS. THE ENGS HAD NOT APPARENTLY SPOOLED DOWN COMPLETELY. 1 PROP BLADE ON THE R ENG HAD DRUG THE GND AND BENT AFT. THE L ENG HAD STOPPED WITH THE PROP IN A POS THAT HAD NOT TOUCHED THE GND WITH ANY SIGNIFICANCE. LATER; MECHS HAD FOUND AN O-RING SEAL HAD FAILED IN THE R BRAKE ASSEMBLY (FOR WANT OF A NAIL). MY BEST ASSESSMENT OF WHAT OCCURRED IS THAT THE WX HAD BEEN MILD; FOLLOWED BY A COLD SNAP. THIS MAY HAVE CONTRIBUTED TO THE O-RING FAILURE; ALTHOUGH OUTSIDE AIR TEMP ENRTE AT 5000 FT HAD BEEN 42 DEGS F. ENRTE; THE BRAKE FLUID BEGAN LEAKING OUT. AFTER LNDG AND DURING TAXIING; USING THE R BRAKE HAD PUMPED THE REMAINING USEFUL FLUID OUT. WHILE WBOUND ON TXWY G; HAVING DEPLETED THE BRAKE FLUID IN THE R SIDE; ONLY THE L BRAKE WAS CONTRIBUTING TO CTLING TAXI RATE. THE L BRAKE MAY HAVE BECOME HOT AND NOT WORKING AT ITS OPTIMUM (FADING). FULL R RUDDER DEFLECTION HAD EXPOSED MORE CTL SURFACE TO THE TAILWIND. AFTER HAVING NOTIFIED COMPANY MGMNT OF THE PROB; I RECEIVED A PHONE CALL; A MR. A OF THE DU PAGE FSDO. I RELATED THE ABOVE EVENT TO HIM. HE ASKED OF MY IMMEDIATE INTENTIONS; AND I TOLD HIM I WOULD BE AVAILABLE TO TALK WITH HIM AT THE LCL FBO UNTIL NOON; IF NOT LATER. AFTER SUNRISE; LCL MAINT RETRIEVED THE ACFT FROM THE MISHAP SITE. AS I SPOKE WITH MECHS; I LEARNED FAA PERSONNEL HAD ALREADY INSPECTED THE ACFT. THE DIRECTOR OF MAINT FOR MY COMPANY ARRIVED; INSPECTED AND PHOTOED THE ACFT AND SPOKE WITH LCL MAINT. WE DEPARTED DPA SHORTLY AFTER VIA COMPANY ACFT; AND ARRIVED BACK AT 3SQ. I HAD MESSAGE TO CALL A MR. B OF THE DPA FSDO. HAVING HAD ONLY 1 1/2 HRS OF SLEEP IN THE PRIOR 30 HRS; I ELECTED TO GO HOME AND RETIRE. I LATER PHONED MR. B AND REITERATED THE ABOVE EVENTS. I THEN ANSWERED HIS QUESTIONS REGARDING RECURRENCY; TOTAL TIME; TIME IN ACFT; ETC. HIS PARTING STATEMENT WAS TO THE EFFECT 'I THINK WE'LL PROBABLY WRITE THIS OFF AS A MAINT IRREGULARITY INCIDENT.' ALTHOUGH I SAID NOTHING AT THE TIME; THIS LEFT ME RATHER VEXED. MY UNDERSTANDING OF NTSB 830 IS THAT THIS OCCURRENCE QUALIFIED NEITHER AS AN ACCIDENT NOR AN INCIDENT. PERHAPS I'M HUNG UP ON SEMANTICS; BUT MR. B'S VAGUENESS WASN'T REASSURING. THE COMPANY HAD BEEN DENIED AUTHORIZATIONFOR A PROGRESSIVE MAINT SCHEDULE PROGRAM AND RELEGATED TO THE BASIC 100 HR/ANNUAL SCHEDULE. WITH THE COMPANY'S LEVEL OF ACTIVITY; A LOT OF ACFT PARTS CAN WEAR/FAIL IN LESS THAN 100 HRS. WHILE MR. B QUESTIONED ME ABOUT OUR TRAINING CURRICULA INCLUDING SPECIFIC WEAR TOLERANCE OF ACFT BRAKES; I COULDN'T HELP BUT THINK OF THE FAA'S AND DPA ARPT AUTH'S SNOW BERM HT TOLERANCES. GRANTED; IT'S DECEMBER IN CHICAGO; BUT THE FIRST SNOW FALL AT DPA WAS MORE THAN A WK PRIOR TO THIS MISHAP. THE LCL TEMP HAD RISEN ABOVE AND FALLEN BELOW FREEZING SEVERAL TIMES. YET; PLOWED SNOW WAS NOT REMOVED AROUND RWY/TXWY PERIMETERS. THIS; IN EFFECT; CREATED ROCK-SOLID BARRIERS AT ALL PERIMETERS. HAD THIS EVENT OCCURRED AT ANY OTHER SEASON; THE ACFT MAY HAVE EXITED THE TXWY ONTO GRASS OUTFIELD AND AT WORSE; STUCK IN THE MUD. AS IT IS NOW; A SIZEABLE ACFT INSURANCE CLAIM AND A THREAT TO MY AIRMEN'S PRIVILEGES.