Individually Owned: 150,657
Corporate Owned: 137,281
Memphis International Airport
Aircraft Accident/Incident Report
Memphis, Tennessee
Friday, July 28, 2006 11:25 CDT
NTSB Narrative Summary Released at Completion of Accident
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.
NTSB Probable Cause Narrative
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.
Event Information
| Type of Event | Accident |
| Event Date | 7/28/2006 |
| Event Day of the Week | Friday |
| Time of Event | 1125 |
| Event Time Zone | Central Daylight Time |
| Event City | Memphis |
| Event State | TENNESSEE |
| Event Country | -- |
| Zipcode of the event site | -- |
| Event Date Year | 2006 |
| Event Date Month | 7 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | Memphis International |
| Event Location Nearest Airport ID | KMEM |
| 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 | 341 |
| Weather Briefing Completeness | -- |
| Investigator's weather source | Weather Observation Facility |
| Time of the weather observation | 1630 Coordinated Universal Time? Same as GMT |
| Direction of event from weather observation facility (degrees) | -- |
| Weather Observation Facility ID | MEM |
| Elevation of weather observation facility | 341 |
| Distance of event from weather observation facility (units?) | -- |
| Time Zone of the weather observation | UTC |
| Lighting Conditions | Day |
| Lowest Ceiling Height | 15000 |
| Lowest Non-Ceiling Height | 7500 |
| Sky/Lowest/Cloud Conditions | Few |
| Sky Condition for Lowest Ceiling | Overcast |
| Visibility Runway Visual Range (Feet) | -- |
| Visibility Runway Visual Value (Statute Miles) | -- |
| Visibility (Statute Miles) | 10 |
| Air Temperature at event time (in degrees celsius) | 26 |
| Dew Point at event time (in degress fahrenheit) | 18 |
| Wind Direction (degrees magnetic) | 270 |
| Variable Wind Indicator | Wind direction could be determined |
| Wind Speed (knots) | 14 |
| Wind Velocity Indicator | -- |
| Wind Gust Indicator | Gusting |
| Wind Gust (knots) | 18 |
| Altimeter Setting at event time (in. Hg) | 30.15 |
| 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 | 3 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 24782 |
| NTSB Notification Source | FAA |
| NTSB Notification Date | Jul 28 2006 12:00AM |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Dec 16 2008 5:11PM |
| User who most recently changed record | schd |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N391FE |
| NTSB Number | DCA06FA058 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | IFR |
| Flight plan Was Activated? | Yes |
| Damage | Substantial |
| Aircraft Fire | Ground |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BOEING |
| Aircraft Model | MD-10-10F |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 46625 |
| Certified Max Gross Weight | 443000 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | 3 |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 3 |
| Number of Engines | 3 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | AAIP |
| Date of Last Inspection | Jul 28 2006 12:00AM |
| Airframe hours since last inspection | -- |
| Airframe Hours | 73283 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | Unknown |
| Aircraft Owner Name | Federal Express Corp. |
| Aircraft Owner Street Address | -- |
| Aircraft Owner City | Memphis |
| Aircraft Owner State | TN |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | -- |
| Operator is an individual? | No |
| Operator Name | FEDERAL EXPRESS CORP |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | -- |
| Operator City | Memphis |
| Operator State | TN |
| Operator Country | USA |
| Operator Zip code | -- |
| Operator Code | FDEA |
| Owner has at least one certificate | Yes - certificate holder |
| Other Operator of large aircraft? | No |
| Certified for Part 133 or 137 Operation | -- |
| Operator Certificate Number | -- |
| Indicates whether an air carrier operation was scheduled or not | Non-scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Cargo |
| Type of Flying (Per_Bus / Primary) | -- |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | No |
| Departure Airport Code | SEA |
| Departure City | SEATTLE |
| Departure State | WA |
| Departure Country | USA |
| Departure Time | 1257 |
| Departure Time Zone | UTC |
| Destination Same as Local Flt | crash at destination city |
| Destination Airport Code | KMEM |
| Destination City | Memphis |
| Destination State | TN |
| Destination Country | USA |
| Specific Phase of Flight | Landing - roll |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Jul 10 2009 9:56AM |
| User who most recently changed record | grol |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | 18R |
| Runway Length | 9329 |
| Runway Width | 150 |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |