Individually Owned: 150,657
Corporate Owned: 137,281
Ted Stevens International Airport
Aircraft Accident/Incident Report
Anchorage, Alaska 99502
Wednesday, October 9, 2002 17:40 AKD
NTSB Narrative Summary Released at Completion of Accident
The instrument flight rules scheduled international flight was in cruise flight at FL350 with the autopilot engaged, when it abruptly rolled into a 30 to 40 degree left bank. There were indications that the lower rudder moved to the left blowdown limit, and remained there. Emergency procedures failed to correct the problem, and the flight diverted to the nearest airport for an emergency landing. As the airspeed decreased during the approach, the lower rudder deflected further to the left. The flightcrew used asymmetric engine thrust to maintain heading. After landing, the lower rudder remained deflected fully to the left, and could not be repositioned until the hydraulic pressure was relieved. An inspection of the forged aluminum manifold of the lower rudder power control module (PCM) revealed the end portion which houses the yaw damper actuator had fractured off from the main portion of the manifold. The lower rudder PCM and the flight data recorder (FDR) were sent to the NTSB laboratory. The data retrieved from the FDR showed an initial lower rudder deflection of 17.5 degrees left, and a subsequent increase to 32 degrees (full) left. The incident airplane has two independently supported and operated rudders, which provide yaw control. Typically, the upper and lower rudders operate in unison. The hydraulic actuators for the lower and upper rudders are controlled by independent power control modules. The power control modules for both the upper and lower rudders are virtually identical. The fractured power control module was disassembled and inspected. The yaw damper piston was protruding from the fracture, and precluded functional testing of the module. The individual components of the power control module were tested, and no anomalies were found. Dimensional checks showed no discrepancies, and metallurgical testing showed the manifold material was consistent with the manufacturer's specifications. Metallurgical examination revealed a mode of crack initiation and growth consistent with fatigue. A non-destructive inspection process was developed, and a group of similar power control modules were inspected. The group contained power control modules with higher and lower use cycles than the incident airplane's power control module. No similar fractures were found. As a result of this incident, the airplane's manufacturer has issued an Alert Service Bulletin which recommends operators perform an ultrasonic inspection on pertinent high-time lower and upper rudder power control modules. The Federal Aviation Administration has issued a Notice of Proposed Rule Making for a airworthiness directive which would make the ultrasonic inspection mandatory for all affected airplanes.
NTSB Probable Cause Narrative
The fatigue fracture of the lower rudder power control module manifold, which resulted in a lower rudder hardover.
Event Information
| Type of Event | Incident |
| Event Date | 10/9/2002 |
| Event Day of the Week | Wednesday |
| Time of Event | 1740 |
| Event Time Zone | -- |
| Event City | Anchorage |
| Event State | ALASKA |
| Event Country | -- |
| Zipcode of the event site | 99502 |
| Event Date Year | 2002 |
| Event Date Month | 10 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | 611028N |
| Event Location Longitude | 1495947W |
| Event Location Airport | Ted Stevens International |
| Event Location Nearest Airport ID | PANC |
| Indicates whether the acc/inc occurred off or on an airport | On Airport |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Full |
| Investigator's weather source | Pilot |
| Time of the weather observation | |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | -- |
| Elevation of weather observation facility | -- |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | -- |
| 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) | -- |
| Air Temperature at event time (in degrees celsius) | -- |
| Dew Point at event time (in degress fahrenheit) | -- |
| Wind Direction (degrees magnetic) | -- |
| Variable Wind Indicator | -- |
| Wind Speed (knots) | -- |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Unknown |
| Wind Gust (knots) | -- |
| Altimeter Setting at event time (in. Hg) | -- |
| 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 | 404 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 14693 |
| NTSB Notification Source | FAA Anchorage, ROC |
| NTSB Notification Date | Oct 9 2002 12:00AM |
| NTSB Notification Time | 1744 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Jun 29 2004 8:02AM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | Anchorage FSDO-03 |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N661US |
| NTSB Number | ANC03IA001 |
| 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 | 747-400 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 23719 |
| Certified Max Gross Weight | 873000 |
| 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 | 429 |
| Number of Engines | 4 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Conditional |
| Date of Last Inspection | Aug 30 2001 12:00AM |
| Airframe hours since last inspection | 5209 |
| Airframe Hours | 50090 |
| ELT Installed | No |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | -- |
| Aircraft Owner Name | State Street Bank and Trust Company Trustee |
| Aircraft Owner Street Address | PO Box 778 |
| Aircraft Owner City | Boston |
| Aircraft Owner State | MA |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 02102 |
| Operator is an individual? | No |
| Operator Name | NORTHWEST AIRLINES INC |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | 6300 Boeing Ave. |
| Operator City | Anchorage |
| Operator State | AK |
| Operator Country | USA |
| Operator Zip code | 99502 |
| Operator Code | NWAA |
| 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 | No |
| Departure Airport Code | DTW |
| Departure City | Detroit |
| Departure State | MI |
| Departure Country | USA |
| Departure Time | 1403 |
| Departure Time Zone | EDT |
| Destination Same as Local Flt | -- |
| Destination Airport Code | NRT |
| Destination City | Narita |
| Destination State | -- |
| Destination Country | JA |
| Specific Phase of Flight | Cruise - normal |
| Report sent to ICAO? | Yes |
| Evacuation occurred | No |
| Date of most recent change to record | Nov 26 2003 1:19PM |
| User who most recently changed record | PETL |
| Since inspection or accident | Last Inspection |
| Event Location Runway Number and Location | -- |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |