Individually Owned: 151,845
Corporate Owned: 143,699
Subic Bay International Airport
Aircraft Accident/Incident Report
Subic Bay
Sunday, June 2, 2002 16:00 UTC
NTSB Narrative Summary Released at Completion of Accident
As the MD-11F airplane was on final approach to landing, the flight crew selected flaps 50 (full extension) and continued to approach the runway. About one minute later, the flight crew heard a loud bang and felt the airplane shudder. The airplane then began to roll to the left, and nearly full right control wheel input was required to counter the left roll. The flight crew performed a missed approach, declared an emergency, and diverted to another airport. During the landing, the airplane experienced a tailstrike. The flight control malfunction was initiated by the failure of the bolt assemblies securing the left inboard flap outboard hinge to the wing trailing edge. The lower outboard nut failed first due to stress corrosion cracking. The lower inboard bolt failure was initiated by fatigue and was completed by overload following the failure of the nut on the lower outboard bolt. The two upper bolts failed by overload following the failure of both lower bolt assemblies. The failure of all four bolt assemblies allowed the flap hinge to pull free from the wing trailing edge, drop and jam the left, inboard flap at the fully extended position. The separating flap hinge pulled the components of the left hand spoiler system from their original position resulting in the deployment of spoilers L1, L4, and L5. The deployment of three of the five left-hand spoilers caused the uncommanded left roll of the aircraft. Hydraulic system no. 3 was also damaged when the flap hinge separated allowing the hydraulic fluid to drain out of the system. Once the hydraulic quantity is depleted, the number three spoilers on each wing will not operate. According to Boeing engineers, the loss of the R3 spoiler would affect the ability of the right wing flight controls to counter the left roll of the aircraft. The airplane was originally used as a manufacturer flight test airplane. The impact of the flight-testing of the airplane to the overall fatigue life of the flap hinge bolts could not be determined. Prior to the accident, there were no requirements for the inspection of the flap hinge bolt assemblies on MD-11 aircraft. The manufacturer issued a service bulletin after the accident recommending inspection and/or replacement of the flap hinge, lower bolt assemblies. The bulletin recommends changing from alloy steel bolts and nuts to Inconel. Inconel is a nickel-based alloy that is highly resistant to general corrosion and stress corrosion cracking, which can occur in low alloy, high strength steel. The FAA issued an Airworthiness Directive mandating the Service Bulletin.
NTSB Probable Cause Narrative
The failure of the lower outboard nut and bolt assembly of the left inboard flap's outboard hinge that resulted from stress corrosion cracking and fatigue. Factors contributing to the accident were the inadequate materials specification of the bolt, and inadequate inspection requirements for the assembly.
Event Information
| Type of Event | Accident |
| Event Date | 6/2/2002 |
| Event Day of the Week | Sunday |
| Time of Event | 1600 |
| Event Time Zone | Coordinated Universal Time? Same as GMT |
| Event City | Subic Bay |
| Event State | -- |
| Event Country | -- |
| Zipcode of the event site | -- |
| Event Date Year | 2002 |
| Event Date Month | 6 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | Subic Bay International |
| Event Location Nearest Airport ID | SFS |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | 1 |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | Full |
| Investigator's weather source | Witness |
| 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 | Not Gusting |
| 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 | 2 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | 19074 |
| NTSB Notification Source | NTSB Comm. Center |
| NTSB Notification Date | Jun 16 2002 12:00AM |
| NTSB Notification Time | 1200 |
| Fiche Number and/or location -used to find docket information | DMS |
| Date of most recent change to record | Dec 20 2005 6:27AM |
| User who most recently changed record | NTSB\JOHB |
| Basic weather conditions | Visual Meteorological Cond |
| FAA District Office | AAI-100 (FAA HQ) |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N601FE |
| NTSB Number | DCA02MA042 |
| 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 | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | McDonnell Douglas |
| Aircraft Model | MD-11F |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 48401 |
| Certified Max Gross Weight | 632000 |
| Aircraft Category | Airplane |
| Aircraft Registration Class | U.S. Registered/Foreign Soil |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | -- |
| Cabin Crew Seats | -- |
| Passenger Seats | -- |
| Total number of seats on the aircraft | 5 |
| Number of Engines | 3 |
| Fixed gear or retractable gear | Retractable |
| Aircraft, Type of Last Inspection | Continuous Airworthiness |
| Date of Last Inspection | Jun 10 2002 12:00AM |
| Airframe hours since last inspection | 88 |
| Airframe Hours | 37443 |
| ELT Installed | Unknown |
| ELT Activated | Unknown |
| ELT Aided Location of Event Site | Unknown |
| ELT Type | -- |
| Aircraft Owner Name | Wilmington Trust Company |
| Aircraft Owner Street Address | Rodney Square North |
| Aircraft Owner City | Wilmington |
| Aircraft Owner State | DE |
| 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 | 38118 |
| Operator Code | FDEA |
| 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 | Non-scheduled |
| Indicates Domestic or International Flight | International |
| 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 | BKK |
| Departure City | Bangkok |
| Departure State | -- |
| Departure Country | TH |
| Departure Time | 1930 |
| Departure Time Zone | UTC |
| Destination Same as Local Flt | -- |
| Destination Airport Code | SFS |
| Destination City | Subic Bay |
| Destination State | -- |
| Destination Country | RP |
| Specific Phase of Flight | Approach - VFR pattern - final approach |
| Report sent to ICAO? | Yes |
| Evacuation occurred | No |
| Date of most recent change to record | -- |
| User who most recently changed record | -- |
| Since inspection or accident | Time of Accident |
| Event Location Runway Number and Location | NA |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |