Individually Owned: 150,657
Corporate Owned: 137,281
Sioux Gateway Airport
Aircraft Accident/Incident Report
Sioux City, Iowa 51102
Wednesday, July 19, 1989 16:00 CDT
NTSB Narrative Summary Released at Completion of Accident
The Safety Board's full report on this investigation is provided as Aviation Accident Report number AAR-90/06. To obtain a copy of this report, or to view the executive summary online, please see the Web site at http://www.ntsb.gov/publictn/publictn.htm
UNITED AIRLINE FLT 232 WAS CRUISING AT FL 370, WHEN THERE WAS A CATASTROPHIC FAILURE OF THE # 2 (TAIL MOUNTED) ENG. THIS WAS DUE TO SEPN, FRAGMENTATION & FORCEFUL DISCHARGE OF THE STAGE 1 FAN ROTOR ASSEMBLY PARTS FM THE #2 ENG (UNCONTAINED FAILURE), WHICH LED TO LOSS OF THE 3 HYD SYSTEMS THAT POWERED THE FLT CTLS. THE FLIGHTCREW EXPERIENCED SEVERE DIFFICULTIES CTLG THE ACFT, WHICH SUBSEQUENTLY CRASHED DRG AN EMERG LNDG AT SIOUX CITY. AN INV REVEALED EVIDENCE CONCERNING LIMITATIONS IN INSPN & QUALITY CTL PROC USED DRG ENG OVERHAUL, WHICH RESULTED IN A FAILURE TO DETECT A FATIGUE CRACK, ORIGINATING FM A PREVIOUSLY UNDETECTED METALLURGICAL DEFECT IN A CRITICAL AREA OF THE STATE 1 FAN DISK. (SEE: NTSB/AAR-90/06)
NTSB Probable Cause Narrative
THE INADEQUATE CONSIDERATION GIVEN TO HUMAN FACTORS LIMITATIONS IN THE INSPECTION AND QUALITY CONTROL PROCEDURES USED BY UNITED AIRLINES' ENGINE OVERHAUL FACILITY WHICH RESULTED IN THE FAILURE TO DETECT A FATIGUE CRACK ORIGINATING FROM A PREVIOUSLY UNDECTECTED METALLURGICAL DEFECT LOCATED IN A CRITICAL AREA OF THE STAGE 1 FAN DISK THAT WAS MANUFACTURED BY GENERAL ELECTRIC AIRCRAFT ENGINES. THE SUBSEQUENT CATASTROPHIC DISINTEGRATION OF THE DISK RESULTED IN THE LIBERATION OF DEBRIS IN A PATTERN OF DISTRIBUTION AND WITH ENERGY LEVELS THAT EXCEEDED THE LEVEL OF PROTECTION PROVIDED BY DESIGN FEATURES OF THE HYDRAULIC SYSTEMS THAT OPERATED THE DC-10'S FLIGHT CONTROLS.
Event Information
| Type of Event | Accident |
| Event Date | 7/19/1989 |
| Event Day of the Week | Wednesday |
| Time of Event | 1600 |
| Event Time Zone | Central Daylight Time |
| Event City | SIOUX CITY |
| Event State | IOWA |
| Event Country | -- |
| Zipcode of the event site | 51102 |
| Event Date Year | 1989 |
| Event Date Month | 7 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | SIOUX GATEWAY |
| Event Location Nearest Airport ID | SUX |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | 0 |
| Degrees magnetic from airport | 0 |
| Airport Elevation | 1098 |
| Weather Briefing Completeness | Not pertinent |
| Investigator's weather source | Unknown |
| Time of the weather observation | 0 |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | SUX |
| Elevation of weather observation facility | 0 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 4000 |
| Lowest Non-Ceiling Height | 0 |
| Sky/Lowest/Cloud Conditions | Unknown |
| Sky Condition for Lowest Ceiling | Broken |
| Visibility Runway Visual Range (Feet) | 0 |
| Visibility Runway Visual Value (Statute Miles) | 0 |
| Visibility (Statute Miles) | 15 |
| Air Temperature at event time (in degrees celsius) | 27 |
| Dew Point at event time (in degress fahrenheit) | 14 |
| Wind Direction (degrees magnetic) | 10 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 11 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 30 |
| Density Altitude (feet) | 0 |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | Fatal |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | 111 |
| Injury Total Minor | 125 |
| Injury Total None | 13 |
| Injury Total Serious | 47 |
| Injury Total All | 283 |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 437 |
| NTSB Notification Source | -- |
| NTSB Notification Date | Jul 19 1989 12:00AM |
| NTSB Notification Time | 1710 |
| Fiche Number and/or location -used to find docket information | 39915 |
| Date of most recent change to record | Dec 13 2000 12:51PM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N1819U |
| NTSB Number | DCA89MA063 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | -- |
| Damage | Destroyed |
| Aircraft Fire | Ground |
| Aircraft Explosion | Ground |
| Aircraft Manufacturer's Full Name | MCDONNELL DOUGLAS |
| Aircraft Model | DC-10-10 |
| Aircraft Series Identifier | DC-10-10 |
| Aircraft Serial Number | 46618 |
| Certified Max Gross Weight | 430000 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | U.S. Registered/U.S. Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 345 |
| Number of Engines | 3 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Unknown |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | 0 |
| Airframe Hours | -- |
| ELT Installed | No |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | |
| Aircraft Owner Street Address | |
| Aircraft Owner City | |
| Aircraft Owner State | |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | |
| Operator is an individual? | -- |
| Operator Name | UNITED AIRLINES |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | P. O. BOX 66100 |
| Operator City | CHICAGO |
| Operator State | IL |
| Operator Country | |
| Operator Zip code | 60666 |
| Operator Code | UALA |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | Unknown |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | Unknown |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | DEN |
| Departure City | DENVER |
| Departure State | CO |
| Departure Country | |
| Departure Time | 1409 |
| Departure Time Zone | CDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | ORD |
| Destination City | CHICAGO |
| Destination State | IL |
| Destination Country | |
| Specific Phase of Flight | Landing |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jan 2 2001 10:30AM |
| User who most recently changed record | dbo |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | 22 |
| Runway Length | 6600 |
| Runway Width | 150 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |