Individually Owned: 150,657
Corporate Owned: 137,281
Minneapolis St Paul Intl Airport
Aircraft Accident/Incident Report
Minneapolis, Minnesota 55425
Tuesady, May 2, 1989 14:40 CDT
NTSB Narrative Summary Released at Completion of Accident
THE FLIGHT CREW REPORTED THAT WHILE IN CRUISE FLIGHT AT 33,000 FEET, THEY EXPERIENCED A HYDRAULIC SYSTEM FAILURE. THEY MANUALLY EXTENDED THE LANDING GEAR FOR LANDING AND MADE AN UNEVENTFUL NO FLAPS/NO SLATS LANDING. POST-ACCIDENT INVESTIGATION REVEALED THAT THE LOSS OF HYDRAULIC PRESSURE IN BOTH SYSTEMS WAS DUE TO THE FAILURE OF PTU S/O VALVE BODY ATTACH SCREWS ON THE LEFT SYSTEM VALVE. THIS ALLOWED THE LEFT VALVE BODY TO SEPERATE FROM THE REMAINING ASSEMBLY, PORTING LEFT SYSTEM HYDRAULIC FLUID OVERBOARD, AND SUBSEQUENTLY DEPRESSURIZING THE RIGHT SYSTEM (ALTHOUGH THERE WAS NO LOSS OF RIGHT SYSTEM HYDRAULIC FLUID). THE MANUFACTURER HAD A RE-DESIGNED, STRONGER UNIT AVAILABLE TO OPERATORS; THIS IMPROVED UNIT HAD STRONGER VALVE BODY ATTACH SCREWS, WELDED VALVE BODIES, STEEL GEARS, AND A SHEAR PIN IN THE MOTOR-TO-VALVE GEAR TRAIN.
NTSB Probable Cause Narrative
FAILURE OF THE HYDRAULIC POWER TRANSFER UNIT SHUT-OFF (PTU S/O) VALVE DUE TO FAILED (FATIGUED) VALVE BODY ATTACH SCREWS.
Event Information
| Type of Event | Incident |
| Event Date | 5/2/1989 |
| Event Day of the Week | Tuesday |
| Time of Event | 1440 |
| Event Time Zone | Central Daylight Time |
| Event City | MINNEAPOLIS |
| Event State | MINNESOTA |
| Event Country | -- |
| Zipcode of the event site | 55425 |
| Event Date Year | 1989 |
| Event Date Month | 5 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | |
| Event Location Longitude | |
| Event Location Airport | MINNEAPOLIS ST PAUL INTL |
| Event Location Nearest Airport ID | MSP |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 0 |
| Degrees magnetic from airport | 0 |
| Airport Elevation | 841 |
| Weather Briefing Completeness | Full |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1500 Central Daylight Time |
| Direction of event from weather observation facility (degrees) | 0 |
| Weather Observation Facility ID | MSP |
| Elevation of weather observation facility | 841 |
| Distance of event from weather observation facility (units?) | 0 |
| Time Zone of the weather observation | CDT |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 7000 |
| 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) | 20 |
| Air Temperature at event time (in degrees celsius) | 13 |
| Dew Point at event time (in degress fahrenheit) | -3 |
| Wind Direction (degrees magnetic) | 290 |
| Variable Wind Indicator | Unknown |
| Wind Speed (knots) | 9 |
| Wind Velocity Indicator | Unknown |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | 0 |
| Altimeter Setting at event time (in. Hg) | 30 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | Unknown |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | 0 |
| On Ground, Minor Injuries | 0 |
| On Ground, Serious Injuries | 0 |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 96 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 5030 |
| NTSB Notification Source | -- |
| NTSB Notification Date | May 2 1989 12:00AM |
| NTSB Notification Time | 2010 |
| Fiche Number and/or location -used to find docket information | 39509 |
| Date of most recent change to record | Dec 13 2000 12:40PM |
| User who most recently changed record | dbo |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N434AA |
| NTSB Number | CHI89IA083 |
| Missing Aircraft Indicator | N |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | -- |
| Damage | Minor |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | MCDONNELL DOUGLAS |
| Aircraft Model | DC-9-82 |
| Aircraft Series Identifier | DC-9-82 |
| Aircraft Serial Number | 49452 |
| Certified Max Gross Weight | 140000 |
| 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 | 172 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | -- |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | AMERICAN AIRLINES |
| Aircraft Owner Street Address | PO BOX 619616 DFW AIRPORT |
| Aircraft Owner City | DALLAS FT WORTH |
| Aircraft Owner State | TX |
| Aircraft Owner Country | |
| Aircraft Owner Zipcode | 75261 |
| Operator is an individual? | -- |
| Operator Name | |
| Operator Same as Owner? | Yes |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | Yes |
| Operator Street Address | |
| Operator City | |
| Operator State | |
| Operator Country | |
| Operator Zip code | |
| Operator Code | AALA |
| 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/Cargo |
| Type of Flying (Per_Bus / Primary) | Unknown |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | SEA |
| Departure City | SEATTLE |
| Departure State | WA |
| Departure Country | |
| Departure Time | 940 |
| Departure Time Zone | PDT |
| 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 | 29L |
| Runway Length | 10000 |
| Runway Width | 200 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |