Boeing 747-400 incident near Anchorage, Alaska, October 10, 2002
On October 10, 2002 at about 1:40 am local time, a Boeing 747-400, registered N661US, was involved in an incident near Anchorage, Alaska (Ted Stevens International airport). It was flown under scheduled airline rules (Part 121). No one was hurt; 404 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The fatigue fracture of the lower rudder power control module manifold, which resulted in a lower rudder hardover.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 10, 2002 · about 1:40 am local time
- Place
- Anchorage, Alaska · Ted Stevens International · map
- Type
- Incident
- Injuries
- No one was hurt; 404 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Boeing 747-400 · all 747-400s on the register
- Registration
- N661US · registry record · serial 23719
- Damage
- Not recorded
- Flight
- Flight · scheduled airline rules (Part 121)
The NTSB's narrative final · quoted from the NTSB record
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.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instrument: airplane
- Flight time: 11,297 hours in all; 630 in this make and model; 43 in the last 90 days; 10 in the last 30 days
- Last flight review: April 22, 2002
- Medical certificate: Class 1 (valid medical--w/ waivers/lim.)
- Seat: left
- Injury: no injuries
Co-pilot
- Certificate: airline transport pilot, flight engineer
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 3,420 hours in all; 651 in this make and model; 129 in the last 90 days; 63 in the last 30 days
- Last flight review: January 15, 2002
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: rgt
- Injury: no injuries
The aircraft
- Airframe total time: 50,090 hours
- Last inspection: condition inspection, August 30, 2001; 5,209 hours since
- Maximum gross weight: 873,000 lb
- Seats: 429
- Landing gear: retractable
- Engine: Pratt & Whitney PW4056 (turbofan); 0 hours total
- Operator: Northwest Airlines INC
The flight
- Departed from: DTW Detroit MI at 6:03 pm
- Destination: NRT Narita
- Flight plan: IFR
- A second pilot was aboard
Weather at the time
- Light: night
- Sky: clear
- Temperature: 0°F (-18°C), dew point 0°F (-18°C)
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 18 | |||
| Passengers | 386 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Other NTSB records under N661US the same tail number, which may have belonged to a different aircraft at the time
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.