Northwest Airlines Flight 85
Boeing 747-400 · Rudder hardover due to metal fatigue
From Detroit Metropolitan Wayne County Airport (DTW) to Narita International Airport (NRT)
Event
- NTSB case
- ANC03IA001
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Incident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- Event fatalities
- 0 · all aircraft and ground
- Ground fatalities
- Unknown
- Occupants
- 404
- Survivors
- 404
- InjuriesFatal: death within 30 days. Serious: over 48 hours in hospital within a week, most broken bones, severe bleeding, nerve or organ damage, or serious burns. Minor: anything less. Glossary
- 0 serious · 0 minor (NTSB)
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- Airline
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Boeing 747-400
- Flight
- NW85
- Aircraft type
- Boeing 747
- Category
- Airplane
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N661US
- Operator
- Northwest Airlines
- Onboard fatalities
- Unknown
- Route
- From Detroit Metropolitan Wayne County Airport (DTW), Detroit, MITo Narita International Airport (NRT), Narita
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 121: Air Carrier
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Airframe, component or system failure
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- None
Cause areas
- Flt control syst, rudder control › Fatigue
- Flt control syst, rudder control › Fractured
Approximate · Coordinates from the NTSB case API, which marks them as estimated or does not say; no uncertainty radius is established.
From the Wikipedia article
Northwest Airlines Flight 85 was a scheduled international passenger flight from Detroit Metropolitan Wayne County Airport in the United States to Narita International Airport in Japan. On October 9, 2002, while over the Bering Sea, the Boeing 747-400 experienced a lower rudder hardover event, which occurs when an aircraft's rudder deflects to its travel limit without crew input. The 747's hardover gave full left lower rudder, requiring the pilots to use full right upper rudder and right aileron to maintain attitude and course.
The flight diverted to Ted Stevens Anchorage International Airport. No passengers or crew were injured, but the incident resulted in an airworthiness directive to prevent the possibility of a future accident.
Incident flight
The flight departed Detroit Metropolitan Wayne County Airport at 2:30 p.m. Eastern Daylight Time. The incident occurred at 5:40 p.m. Alaska Daylight Time, around seven hours into the flight. At the time of the incident, Junior Captain Frank Geib and First Officer Mike Fagan had just taken control of the aircraft, allowing Senior Captain John Hanson and First Officer David Smith to rest. Flight 85's captain said that the event occurred at FL350 (35,000 feet/11,000 meters).
The aircraft abruptly entered a 30- to 40-degree left bank. Geib initially believed that an engine failure had occurred. Hanson reentered the cockpit and continued to fly the aircraft by hand with Fagan. Geib declared an emergency and began a diversion to Anchorage. While the crew tried to declare the emergency, the plane was in a communications dead zone between North America and Asia. Even with a weak signal, the crew contacted another Northwest Airlines flight, Flight 19, which helped Flight 85 declare the emergency as it was closer to Alaska. Flight 85's captain reported that none of the emergency procedures available could correct the problem. The pilots established a conference call with Northwest Airlines in the Minneapolis-St. Paul area, but the employees there were unable to find a solution to the sudden bank. The flight crew took back control of the aircraft and landed at Ted Stevens Anchorage International Airport. To steer the aircraft, they had to use the ailerons and asymmetric engine thrust, applying more engine power to one side than the other.
Hanson said that crew resource management (CRM) contributed to the flight's safe landing at Anchorage:
The incident did not initially receive media attention.
Investigation and cause
Investigation
The National Transportation Safety Board (NTSB) and Boeing launched investigations into the incident. NTSB investigator Carolyn Deforge, who oversaw the investigation, recounted in an interview on the television program Mayday: "It appeared to be a very dramatic event, and... it definitively seemed like something we needed to follow up on, trying to understand what had happened."
The NTSB found that there was a fatigue crack in the power control module and that it was not possible to visually inspect that type of failure. The lower rudder control module's cast metal housing had broken. The end portion of the control module housing that housed the yaw damper actuator had separated from the main portion of the housing. Deforge said in the Mayday episode that the NW85 failure was unusual because most failures are of internal components rather than of the housing itself.
The NTSB ruled that the probable cause was a "fatigue fracture of the lower rudder power control module manifold, which resulted in a lower rudder hardover." In a rudder hardover, the rudder is driven to its full deflection and stays there.
Text from the Wikipedia article “Northwest Airlines Flight 85” (revision 1346581032, retrieved 2026-09-18) by its authors, under CC BY-SA 4.0. Extracted as plain text: references, tables, images and some sections are left out. Read the article
NTSB narrative
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.
Probable cause
The fatigue fracture of the lower rudder power control module manifold, which resulted in a lower rudder hardover.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
Wikipedia article: Northwest Airlines Flight 85
- Article
- Northwest Airlines Flight 85
- Revision
- 1346581032 · 2026-04-01 · retrieved 2026-09-18
- Wikidata
- Q7059927
- Licence
- Text CC BY-SA 4.0, by the article's authors; Wikidata CC0; town positions GeoNames (CC BY 4.0)
NTSB record ANC03IA001
- Event ID
- 20021018X05344
- Case number
- ANC03IA001
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Where each value comes from
- Record
- Wikipedia article "Northwest Airlines Flight 85" (page 38008989, revision 1346581032); merged with NTSB case ANC03IA001 (events / aircraft)
- Date
- NTSB record ANC03IA001: NTSB narrative opening date, consistent with the API date and time (local date)
- Place and country
- Wikipedia infobox: site; country from Wikidata (P17); country from NTSB record ANC03IA001
- Map position
- NTSB record ANC03IA001: NTSB API eventLatitude/eventLongitude
- Aircraft, operator and route
- NTSB record ANC03IA001: aircraft; gaps from Wikipedia infobox: aircraft type, registration, operator, origin and destination; route airports from the linked airport articles' Wikidata codes (OurAirports)
- Operation
- NTSB record ANC03IA001: operated under Part 121: Air Carrier
- Fatalities
- NTSB record ANC03IA001: NTSB API totalFatal
- Ground fatalities
- NTSB record ANC03IA001: events.inj_f_grnd
- Summary
- Wikipedia infobox: summary
Source notes (3)
- One occurrence in two sources, merged: the Wikipedia article "Northwest Airlines Flight 85" and NTSB case ANC03IA001, matched by the same aircraft registration and date. For this US event the NTSB's values are used where the two differ; each value names its source.
- Filled from the NTSB case API where the bulk record had no value: local date, investigation status, coordinates, damage. Values present in the bulk record are kept.
- The date is the local date; the NTSB stores the UTC date 2002-10-10.