Delta B744 at Detroit on Oct 23rd 2011, engine shut down in flight, uncontained engine failure

Last Update: December 8, 2012 / 11:37:51 GMT/Zulu time

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Incident Facts

Date of incident
Oct 23, 2011

Aircraft Registration
JA73NE

Aircraft Type
Boeing 747-400

ICAO Type Designator
B744

The NTSB released their preliminary report reporting the aircraft was climbing through 5000 feet when the crew heard a large compressor stall. After the engine rolled back the crew felt a muffled explosion, a #2 engine fire indication illuminated and the #2 throttle was reduced to idle. The fire indication extinguished after the first fire bottle was discharged.

A post flight inspection revealed three burn-through holes on the #2 (left hand inboard) engine outboard core cowl, punctures and holes at the left hand wing, flaps and ailerons, the #2 engine strut fairings and panels as well as at the left hand horizontal stabilizer.

There was severe damage to the low pressure turbine (LPT) with many blades and vanes missing from various stages, after opening the fan cowls, thrust reverser and core cowls revealed thermal distress and sooting from the fan exit rear case to the rear turbine case, numerous exit hole penetrations and a punctured #4 bearing compartment oil pressure supply line.

Further examination at the engine manufacturer showed there was no damage upstream of the stage 3 LPT, all the LPT blades had fractured transversely across the airfoil at the blade platform, numeours vane clusters were missing or badly battered, one stage 3 LPT outer transition duct segment and two stage 3 LPT vane clusters missing from their normally installed positions, the majority of the stage 3 LPT outer transition duct segment rear seal plates were damaged, broken, and loose.

The NTSB reported that this event marked "the sixteenth known reported stage 3 outer transition duct segment(s) that either partially or fully disengaged from the rear turbine case", all of them with the riveted seal plate configuration, none of them with the integral seal configuration.

The engine manufacturer had released service bulletin PW4ENG 72-488 in June 2002, that introduced thicker seal plates and larger rivets to address that issue. Following that service bulletin only one other similiar event was recorded.

On Dec 8th 2012 the NTSB released their final report concluding the probable cause of the incident was:

The penetration of turbine blade fragments through the rear turbine case, which punctured the No. 4 bearing oil pressure supply tube, allowing misted oil to contact the hot engine case and ignite the undercowl fire.

Contributing to the incident was the installation of approved (but not preferred) stage 3 low pressure turbine outer transition duct segments with the riveted rear seal configuration and the failure of the engine design to comply with the engine debris containment requirements of 14 Code of Federal Regulations 33.13 and 33.75.
Incident Facts

Date of incident
Oct 23, 2011

Aircraft Registration
JA73NE

Aircraft Type
Boeing 747-400

ICAO Type Designator
B744

This article is published under license from Avherald.com. © of text by Avherald.com.
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