Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Los Angeles, California 90009
Thursday, October 19, 2006 1:00 PDT
NTSB Narrative Summary Released at Completion of Accident
During cruise flight, just after entry into foreign airspace, the flight crew was alerted to a System B hydraulic failure, and they decided to return to, and land in the United States (US). Upon re-entry to US airspace, the flight crew declared an emergency and requested to land at the departure airport. On final approach, about 5 minutes after selecting flaps to 15 and lowering the landing gear, the flight crew was alerted to the System A hydraulic quantity gage, that had dropped to 0 pounds per square inch (psi). At this point both System A LOW PRESSURE LIGHTS illuminated and the airplane went into the manual reversion mode. The flight crew indicated that the airplane was difficult to control; however, they landed uneventfully at the airport. Maintenance personnel for the airline, and the airplane manufacturer, inspected the hydraulic systems. They noted that the initiating event was a failed engine driven pump. The secondary event was a cracked hydraulic line that failed due to fatigue. A metallurgical examination revealed the fatigue fracture initiated at the toe of the welding root where they were able to locate a crack that had propagated through half the perimeter. The airframe manufacturer redesigned the affected tube, part number 272A4451-87, a titanium tube, with part number 272A4451-200, a stainless steel tube.
NTSB Probable Cause Narrative
A complete failure and depressurization of both hydraulic systems due to two separate events: 1) the failure of a engine driven pump on the 'A' system, and 2) the fatigue fracture and failure of a hydraulic line on the 'B' system.
Event Information
| Type of Event | Incident |
| Event Date | 10/19/2006 |
| Event Day of the Week | Thursday |
| Time of Event | 100 |
| Event Time Zone | Pacific Daylight Time |
| Event City | Los Angeles |
| Event State | CALIFORNIA |
| Event Country | -- |
| Zipcode of the event site | 90009 |
| Event Date Year | 2006 |
| Event Date Month | 10 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 335655N |
| Event Location Longitude | 1182449W |
| Event Location Airport | -- |
| Event Location Nearest Airport ID | -- |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 50 Pacific Daylight Time |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | LAX |
| Elevation of weather observation facility | 125 |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | PDT |
| Lighting Conditions | Night |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | Clear |
| Sky Condition for Lowest Ceiling | None |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 17 |
| Dew Point at event time (in degress fahrenheit) | 8 |
| Wind Direction (degrees magnetic) | 110 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 3 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Not Gusting |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | 30.04 |
| Density Altitude (feet) | -- |
| Intensity of Precipitation | -- |
| METAR weather report | -- |
| Event Highest Injury | None |
| On Ground, Fatal Injuries | -- |
| On Ground, Minor Injuries | -- |
| On Ground, Serious Injuries | -- |
| Injury Total Fatal | -- |
| Injury Total Minor | -- |
| Injury Total None | 5 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 23170 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | Oct 19 2006 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Mar 31 2008 11:52AM |
| User who most recently changed record | NTSB\johb |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | FAA Northwest Mtn Region CMO |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N614AS |
| NTSB Number | LAX07IA014 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | Yes |
| Damage | None |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | Boeing |
| Aircraft Model | 737-790 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 30343 |
| Certified Max Gross Weight | 174200 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 177 |
| 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 | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | Alaska Airlines, Inc. |
| Aircraft Owner Street Address | 19300 Pacific Hwy S |
| Aircraft Owner City | Seattle |
| Aircraft Owner State | WA |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 98188 |
| Operator is an individual? | No |
| 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 | ASAA |
| Owner has at least one certificate | -- |
| Other Operator of large aircraft? | -- |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Scheduled |
| Indicates Domestic or International Flight | International |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | -- |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | Yes |
| Departure Airport Code | LAX |
| Departure City | Los Angeles |
| Departure State | CA |
| Departure Country | USA |
| Departure Time | 0 |
| Departure Time Zone | PDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | MMX |
| Destination City | Mexico City |
| Destination State | UN |
| Destination Country | MX |
| Specific Phase of Flight | Cruise - normal |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Feb 27 2008 2:27PM |
| User who most recently changed record | COOS |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |