ATR-72 CAPT ENTERED THE RWY HIGH SPD TURNOFF AT TOO GREAT A SPD AND HIT 2 HIGH SPD TURNOFF LIGHTS.

Narrative

A VISUAL APCH AND LNDG WERE MADE WITHOUT INCIDENT BY THE FO. AS THE ACFT SLOWED TO 70 KTS; I TOOK CTL OF THE ACFT PER COMPANY APPROVED OPERATING PROC. WE LANDED ON RWY 27L IN ATLANTA AND I ATTEMPTED TO EXIT THE RWY AT N4. I OBSERVED THE AIRSPD INDICATOR TO BE BELOW 60 KTS. AFTER AN INITIAL TURN OF ABOUT 20 DEGS OFF RWY HDG; THE NOSEWHEEL STEERING BECAME INEFFECTIVE. WE WERE POINTING AT A GRASS MEDIAN BTWN THE RWY AND A PARALLEL TXWY. I WAS ABLE TO USE DIFFERENTIAL BRAKING TO KEEP THE ACFT OFF OF THE GRASS. HOWEVER; I DID STRIKE 2 TAXI LIGHTS. AS THE ACFT CAME TO A STOP; THE NOSE LURCHED TO THE R AND I AGAIN HAD CTL OF THE NOSEWHEEL STEERING. I WAS ABLE TO TAXI TO THE GATE AFTER A BRIEF STOP TO MAKE A PA ANNOUNCEMENT AND HAVE ANOTHER COMPANY PLT INSPECT MY TIRES. SUPPLEMENTAL INFO FROM CAN 577478: AS WE ROLLED OUT; I WAS STILL IN CTL AND I ADDED REVERSE PWR. AT THAT TIME; MY CAPT CALLED OVER '70 KTS; MY CTLS' WHICH IS THE CORRECT CALLOUT AND PROC TO DO. CAPT THEN TOOK CTL OF THE ACFT WHICH WAS STILL ON THE CTRLINE OF RWY 27L. THE ONLY THING I HAD CTL OF THEN WAS THE AILERONS AND ELEVATOR; WHICH I HAD INTO THE WIND AT THAT TIME. AS WE BEGAN TO EXIT THE RWY TO JOIN TXWY N4; THE ACFT BEGAN TO STEER TOWARDS THE OUTSIDE OF THE CTRLINE OF THE HIGHSPD TAXI. I IMMEDIATELY APPLIED FULL AILERON AND FORWARD PRESSURE ON THE YOKE TO SEE IF I COULD GET THE ACFT BACK ON THE HIGH SPD CTRLINE. AT THAT TIME OUR AIRSPD INDICATOR HAD GONE BELOW ITS LOWEST INDICATION OF 60 KTS. THE ACFT PROCEEDED TO COME OFF THE TXWY ONTO THE SHOULDER BUT DID NOT GO INTO THE GRASS. IT WAS UNCLR IF WE RAN OVER ANYTHING. SUBSEQUENTLY CAME TO A FULL STOP ON THE HARD SURFACED SHOULDER; ASSESSED THE SIT AND TAXIED IN. NO ONE WAS INJURED; NO DAMAGE TO ACFT. TWR DID SAY THERE WAS 1 TAXI LIGHT HIT. THE CAPT WAS A 'HIGH MINIMUMS' CAPT; WHICH MEANS HE HAD LESS THAN 100 HRS IN TYPE. THE WIND WAS RPTED ON THE ATIS AS 200 DEGS AT 9 KTS GUSTING TO 14 KTS. THE CREW WAS FRESH; NO FATIGUE. THIS PARTICULAR TYPE OF ACFT (ATR-72) HAS NO NOSEWHEEL STEERING VIA THE RUDDER PEDALS; AND AT TIMES CAN BE A CHALLENGE TO CTL AT THE HIGHER GND SPDS. THE BRAKING SYS ON THIS ACFT IS VERY SENSITIVE AND WHEN APPLIED; THEY TEND TO GRAB AND LURCH THE ACFT FROM SIDE-TO-SIDE AT TIMES. AS A FO; I HAVE BEEN IN THE ACFT AND HAVE TAKEN THE HIGH SPD TXWYS IN VERY SIMILAR SITS AND HAVE NEVER ENCOUNTERED THIS TYPE OF PROB BEFORE. THE ONLY WAY TO POSITIVELY STEER THE ATR-72 ON THE GND IS VIA THE TILLER; WHICH IS LOCATED ON THE CAPT'S SIDE. FO HAS NO TILLER.