AN ATR72 SUFFERS CATASTROPHIC ENG FAILURE DURING TKOF AT ORD. FLC ACCOMPLISHES A SAFE ABORT AND RETURNS PAX TO GATE.

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WE EXPERIENCED A TOTAL ENG FAILURE OF THE #1 ENG DURING THE TKOF ROLL AT APPROX 100 KTS. THE CAPT HAD YIELDED CTL OF THE ACFT TO ME AND WAS MONITORING THE INSTS. WE BOTH HEARD A LOUD EXPLOSIVE NOISE. THE ITT PEGGED (APPROX 1200 DEGS C) AND THE ACFT VEERED SHARPLY L. WE BROUGHT IT BACK UNDER CTL ON THE RWY; DETERMINED THAT THERE WAS NO FIRE OR VISIBLE LEAKING FLUIDS AND RETURNED TO THE GATE. THE FLT ATTENDANTS RPTED NO INJURIES TO PAX AND CABIN CREW AND POSTFLT REVEALED NO VISIBLE SIGNS OF DAMAGE TO ACFT OTHER THAN THE PROP WOULD NOT ROTATE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR STATED THAT MAINT FOUND THAT THE HIGH PRESSURE TURBINE SYS FAILED. THE ENG IS A 2 SPOOL CENTRIFUGAL FLOW ENG THAT IS NORMALLY VERY RELIABLE; BUT; IN THIS CASE THE HIGHER PRESSURE TURBINE FAILED. FO WAS FLYING WHEN THE TURBINE TEMP WENT RAPIDLY TO 1200 DEGS C. CAPT PULLED OFF THE PWR TO BOTH ENGS AND FO KEPT THE ACFT ON THE RWY DURING THIS ABORTED TKOF. BOTH FLC MEMBERS HEARD A LOUD EXPLOSIVE BANG; WHICH THEY NOW BELIEVE TO BE WHEN THE ENG HAD A COMPRESSOR STALL AS A RESULT OF THE TURBINE FAILURE. ABORTED TKOF WAS SUCCESSFUL IN THAT NO OTHER DAMAGE RESULTED TO THE ACFT. THERE WAS NO FIRE RESULTING FROM THIS ENG FAILURE. PAX REMAINED CALM AS THE ACFT RETURNED TO THE GATE TO BE REPLACED BY ANOTHER ACFT.