What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) The following is a narrative describin the incident involving a united airlines, inc. mcdonnell-douglas DC-10-10, N1811U at o'Hare international airport, Chicago, IL (ord) on may 01, 1995. United airlines' flight no 492, bound for dulles, aborted the takeoff on runway 9L due to a fire in no 2 engine. The fire extinguished itself. The aircraft returned to the gate where the passengers deplaned in a normal manner. The flight crew reported that after the application of power for takeoff and at approximately 75 knots, they heard a bang. Upon investigation, they noted that no 2 engine power was at 48% and decreasing. They also observed a b-loop warning so they shut the engine down and aborted the takeoff. The tower then informed the crew that they saw smoke from no 2 engine, so the crew fired an extinguisher bottle. Inspection of the no 2 engine revealed that the engine had suffered an uncontained failure in the turbine section of the engine. Debris had exited the core cowlings at the 5:00 and 9:00 positions. The turbine disc appears to be intact, however most of the turbine blades had been sheared from the disc. All turbine blades and discs down stream of the failed turbine had sustained heavy damage. The turbine case had been cut in two over approximately 85% of its circumference. There was no evidence of fire. No damage occurred to any of the tail surfaces. Also, there were no injuries to the passengers, flight crew, or ground personnel. The engine was removed and replaced. The damaged engine was shipped to united airlines' engine overhaul facility, located in san francisco, CA to undergo a teardown inspection. The teardown inspection revealed that the bolts attaching the first low pressure turbine (lpt) disc to the second lpt disc attach flange had failed. This failure allowed the first disc to rub through the lpt stator case. The reason for the bolt failures could not be determined. United airlines has revised their engine overhaul procedures to include the use of only new bolts and nuts at the flange joint as a precaution.
As the FAA filed it
(-23) THE FOLLOWING IS A NARRATIVE DESCRIBIN THE INCIDENT INVOLVING A UNITED AIRLINES, INC. MCDONNELL-DOUGLAS DC-10-10, N1811U AT O'HARE INTERNATIONAL AIRPORT, CHICAGO, IL (ORD) ON MAY 01, 1995. UNITED AIRLINES' FLIGHT NO 492, BOUND FOR DULLES, ABORTED THE TAKEOFF ON RUNWAY 9L DUE TO A FIRE IN NO 2 ENGINE. THE FIRE EXTINGUISHED ITSELF. THE AIRCRAFT RETURNED TO THE GATE WHERE THE PASSENGERS DEPLANED IN A NORMAL MANNER. THE FLIGHT CREW REPORTED THAT AFTER THE APPLICATION OF POWER FOR TAKEOFF AND AT APPROXIMATELY 75 KNOTS, THEY HEARD A BANG. UPON INVESTIGATION, THEY NOTED THAT NO 2 ENGINE POWER WAS AT 48% AND DECREASING. THEY ALSO OBSERVED A B-LOOP WARNING SO THEY SHUT THE ENGINE DOWN AND ABORTED THE TAKEOFF. THE TOWER THEN INFORMED THE CREW THAT THEY SAW SMOKE FROM NO 2 ENGINE, SO THE CREW FIRED AN EXTINGUISHER BOTTLE. INSPECTION OF THE NO 2 ENGINE REVEALED THAT THE ENGINE HAD SUFFERED AN UNCONTAINED FAILURE IN THE TURBINE SECTION OF THE ENGINE. DEBRIS HAD EXITED THE CORE COWLINGS AT THE 5:00 AND 9:00 POSITIONS. THE TURBINE DISC APPEARS TO BE INTACT, HOWEVER MOST OF THE TURBINE BLADES HAD BEEN SHEARED FROM THE DISC. ALL TURBINE BLADES AND DISCS DOWN STREAM OF THE FAILED TURBINE HAD SUSTAINED HEAVY DAMAGE. THE TURBINE CASE HAD BEEN CUT IN TWO OVER APPROXIMATELY 85% OF ITS CIRCUMFERENCE. THERE WAS NO EVIDENCE OF FIRE. NO DAMAGE OCCURRED TO ANY OF THE TAIL SURFACES. ALSO, THERE WERE NO INJURIES TO THE PASSENGERS, FLIGHT CREW, OR GROUND PERSONNEL. THE ENGINE WAS REMOVED AND REPLACED. THE DAMAGED ENGINE WAS SHIPPED TO UNITED AIRLINES' ENGINE OVERHAUL FACILITY, LOCATED IN SAN FRANCISCO, CA TO UNDERGO A TEARDOWN INSPECTION. THE TEARDOWN INSPECTION REVEALED THAT THE BOLTS ATTACHING THE FIRST LOW PRESSURE TURBINE (LPT) DISC TO THE SECOND LPT DISC ATTACH FLANGE HAD FAILED. THIS FAILURE ALLOWED THE FIRST DISC TO RUB THROUGH THE LPT STATOR CASE. THE REASON FOR THE BOLT FAILURES COULD NOT BE DETERMINED. UNITED AIRLINES HAS REVISED THEIR ENGINE OVERHAUL PROCEDURES TO INCLUDE THE USE OF ONLY NEW BOLTS AND NUTS AT THE FLANGE JOINT AS A PRECAUTION.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.