NTSB Identification: LAX92IA397.
The docket is stored on NTSB microfiche number 48059.
Scheduled 14 CFR operation of UNITED AIRLINES
Incident occurred Wednesday, September 23, 1992 in SAN FRANCISCO, CA
Probable Cause Approval Date: 09/28/1993
Aircraft: MCDONNELL DOUGLAS DC 10-10, registration: N1845U
Injuries: 235 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.

A MCDONNELL DOUGLAS AIRCRAFT COMPANY DC 10 SERIES 10 AIRCRAFT EXPERIENCED AN UNCONTAINED FAILURE OF THE NUMBER 1 ENGINE WHILE IN THE CRUISE CLIMB. THE ENGINE HAD SUSTAINED AN UNCONTAINED FAILURE OF THE 14TH THROUGH 16TH STAGE COMPRESSOR SPOOL. ABOUT 11 YEARS BEFORE THE INCIDENT, THE SPOOL WAS DAMAGED BEYOND MAINTENANCE MANUAL LIMITS. THE DAMAGE CONSISTED OF A 360 DEGREE RUB ON THE AFT RIM SURFACE (SURFACE Q) OF THE 16TH STAGE COMPRESSOR. THE SPOOL WAS PLACED IN STORAGE FOR FIVE YEARS AND THEN RETURNED TO SERVICE AFTER BEING REPAIRED. FLIGHT PROFILE STRESSES WERE ANALYZED BY ENGINE MANUFACTURER. ACCORDING TO THE ENGINE MANUFACTURER, PEAK STRESSES IN THE AFT RIM REGION OR SURFACE Q OCCUR AT THE SAME TIME IN THE FLIGHT PROFILE AS THE UNCONTAINED FAILURE.

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

A FRACTURED COMPRESSOR ASSEMBLY.

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