FedEx Express Flight 630
Federal Express Boeing MD-10-10F · Landing gear failure on landing due to metal fatigue leading to runway excursion and fire
From Seattle–Tacoma International Airport (SEA) to Frederick W. Smith International Airport (KMEM)
Event
- NTSB case
- DCA06FA058
- 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
- Accident
- 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
- 3
- Survivors
- 3
- 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
- 3
- 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 MD-10-10F
- Aircraft type
- Boeing MD-10
- 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
- N391FE
- Operator
- Federal Express
- Onboard fatalities
- Unknown
- Route
- From Seattle–Tacoma International Airport (SEA), Seattle, WATo Frederick W. Smith International Airport (KMEM), Memphis, TN
- 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
- Landing · landing roll
- 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
- Gear collapsed
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Substantial
Cause areas
- Landing gear, main gear strut › Failure
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
From the Wikipedia article
FedEx Express Flight 630 was a regular scheduled cargo flight from Seattle-Tacoma International Airport to Memphis International Airport, Memphis, Tennessee. On July 28, 2006, the McDonnell Douglas MD-10-10F
operating the flight, crashed upon landing due to a landing gear failure. The main left undercarriage collapsed seven seconds after touchdown causing the MD-10 to roll off the runway out of control. The aircraft finally came to a stop near taxiway M4 and caught fire. The fire consumed the wing and port engine and the crash and evacuation left everyone onboard injured.
Accident
FedEx Flight 630 was a regular scheduled cargo flight from Seattle-Tacoma International Airport to Memphis International Airport, Memphis, Tennessee, which was operated by the company's 82 McDonnell Douglas MD-10F aircraft. On 28 July, N391FE was conducting a visual approach to runway 18R which was initially flown with the autopilot engaged and coupled to the ILS. The first officer was the pilot flying for the landing. At 1600 feet the airplane was configured for a landing. At 400 feet the autopilot was disconnected, the final approach segment was smooth. Upon touchdown, the left main gear collapsed without warning, causing the left wing to contact the runway, with the jet veering violently to the left and eventually coming to a stop near taxiway M4.
Investigation and cause
Investigation
The NTSB launched an investigation into the crash of the flight. The final report, released in 2008, cited a fatigue crack in the air filler valve hole caused by inadequate maintenance on the aircraft.
Text from the Wikipedia article “FedEx Express Flight 630” (revision 1363814013, 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 approach and landing were stabilized and within specified limits. Recorded data indicates that the loads experienced by the landing gear at touchdown were within the certification limits for an intact landing gear without any pre-existing cracks or flaws. The weather and runway conditions did not affect the landing. The application of braking by the accident crew, and the overall effect of the carbon brake modification did not initiate or contribute to the landing gear fracture. Post-accident modifications to the MD-10 carbon brake system were implemented due to investigative findings for the purposes of braking effectiveness and reliability. Post accident emergency response by the flight crew and ARFF was timely and correct.
The left main landing gear (LMLG) outer cylinder on the accident airplane had been operated about 8 ½ years since its last overhaul where stray nickel plating likely was introduced in the air filler valve hole. Nickel plating is a permissible procedure for maintaining the tolerances of the inner diameter of the outer gear cylinder, however the plating is not allowed in the air filler valve bore hole. Literature and test research revealed that a nickel plating thickness of 0.008" results in a stress factor increase of 35%. At some point in the life of the LMLG, there was a load event that compressively yielded the material in the vicinity of the air filler valve hole causing a residual tension stress. During normal operations the stress levels in the air filler valve hole were likely within the design envelope, but the addition of the residual stress and the stress intensity factor due to the nickel increased these to a level high enough to initiate and grow a fatigue crack on each side of the air filler valve hole. The stresses at the air filler valve hole were examined via development of a Finite Element Model (FEM) which was validated with data gathered from an instrumented in-service Fedex MD-10 airplane. The in-service data and FEM showed that for all of the conditions, the stress in the air filler valve hole was much higher than anticipated in the design of the outer cylinder. Fatigue analysis of the in-service findings and using the nickel plating factor resulted in a significantly reduced fatigue life of the gear cylinder compared with the certification limits. During the accident landing the spring back loads on the LMLG were sufficient to produce a stress level in the air filler valve hole that exceeded the residual strength of the material with the fatigue cracks present.
Probable cause
the failure of the left main landing gear due to fatigue cracking in the air filler valve hole on the aft side of the landing gear. The fatigue cracking occurred due to the presence of stray nickel plating in the air filler valve hole. Contributing to this was the inadequate maintenance procedures to prevent nickel plating from entering the air filler valve hole during overhaul.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
Wikipedia article: FedEx Express Flight 630
- Article
- FedEx Express Flight 630
- Revision
- 1363814013 · 2026-07-12 · retrieved 2026-09-18
- Wikidata
- Q18207072
- Licence
- Text CC BY-SA 4.0, by the article's authors; Wikidata CC0; town positions GeoNames (CC BY 4.0)
NTSB record DCA06FA058
- Event ID
- 20060808X01115
- Case number
- DCA06FA058
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Where each value comes from
- Record
- Wikipedia article "FedEx Express Flight 630" (page 44021449, revision 1363814013); merged with NTSB case DCA06FA058 (events / aircraft)
- Date
- NTSB record DCA06FA058: NTSB narrative opening date, consistent with the API date and time (local date)
- Place and country
- Wikipedia infobox: site; country from NTSB record DCA06FA058
- Map position
- NTSB record DCA06FA058: events decimal coordinates
- Aircraft, operator and route
- NTSB record DCA06FA058: 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 DCA06FA058: operated under Part 121: Air Carrier
- Fatalities
- NTSB record DCA06FA058: NTSB API totalFatal
- Ground fatalities
- NTSB record DCA06FA058: events.inj_f_grnd
- Summary
- Wikipedia infobox: summary
Source notes (3)
- One occurrence in two sources, merged: the Wikipedia article "FedEx Express Flight 630" and NTSB case DCA06FA058, 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: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.