NTSB Identification: CHI83FA251.
The docket is stored on NTSB microfiche number 21957.
Scheduled 14 CFR UNITED AIRLINES
Accident occurred Saturday, June 11, 1983 in CHICAGO, IL
Aircraft: BOEING 727-222A, registration: N7273U
Injuries: 2 Serious,15 Minor,125 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

DURING THE TAKEOFF ROLL, THE #1 ENG FAILED & THE TAKEOFF WAS ABORTED AT APRX 70 KTS. THE AIRCREW TAXIED THE ACFT CLEAR OF THE RWY & STOPPED ON THE REVERSE HIGH SPEED TURNOFF. THE AIRCREW OF ANOTHER COMPANY ACFT TRANSMITTED THAT THE #1 ENG WAS ON FIRE. THERE WAS NO FIRE WARNING LIGHT IN THE COCKPIT, BUT THE #1 ENG WAS SHUT DOWN & A FIRE EXTINGUISHER WAS DISCHARGED INTO THE ENG. ANOTHER RADIO CALL WAS RECEIVED THAT THE ENG WAS STILL ON FIRE & A SECOND EXTINGUISHER WAS DISCHARGED INTO THE ENG. THE OTHER 2 ENGS WERE ALSO SHUT DOWN & ALL OCCUPANTS WERE EVACUATED USING THE EMERGENCY EXITS. TWO PASSENGERS RECEIVED SERIOUS INJURIES. AN INVESTIGATION REVEALED THE 2ND STAGE TURBINE DISK HAD FRACTURED FROM FATIGUE WHICH INITIATED AT THE BASE OF CAVITIES IN THE BOTTOM OF THE AIR SEAL GROOVE. THE INSIDE & OUTSIDE SURFACESOF THE DISK AIR SEAL GROOVE SHOWED SIGNS OF FRETTING AS IF THE MATING AIR SEAL HAD BEEN MOVING FORE & AFT WITHIN THE GROOVE.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

TURBINE ASSEMBLY,TURBINE WHEEL..CHAFED

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

TURBINE ASSEMBLY,TURBINE WHEEL..FATIGUE

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