NTSB Identification: SEA84IA233.
The docket is stored on NTSB microfiche number 28156.
Scheduled 14 CFR NORTHWEST AIRLINES, INC.
Incident occurred Saturday, September 29, 1984 in SEATTLE, WA
Aircraft: BOEING 747-200B, registration: N613US
Injuries: 172 Uninjured.

NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.

DURING CLIMBOUT, PASSING THRU 4000 FT MSL, THE ACFT EXPERIENCED A FAILURE OF THE #2 ENGINE. THE CREW REPORTED HEARING AN EXPLOSIVE SOUND FOLLOWED BY A DROP IN FUEL FLOW WITH N1 SPEED DECREASING TO 30% RPM ON THE #2 ENGINE. THE ACFT RETURNED TO SEATTLE FOR AN UNEVENTFUL LANDING. THE ENGINE EXHAUST TAIL CONE AND NUMEROUS TURBINE BLADES WERE LOCATED IN A RURAL AREA APRX 11 MILES SOUTH OF THE ARPT. INVESTIGATION REVEALED THE TURBINE STATOR SUPPORT STRUCTURE HAD WEAKENED BY SULFIDATION DUE TO EXHAUST GAGES ESCAPING THRU AN INSPECTION PORT. FAILURE OF THE PORT ALLOWED CONTACT WITH THE TURBINE BLADES, RESULTING IN BLADE ESCAPED AND SUBSEQUENT IMBALANCE.

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

TURBINE ASSEMBLY,NOZZLE SUPPORT..FAILURE,TOTAL

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

TURBINE ASSEMBLY,TURBINE BLADE..SEPARATION

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