Individually Owned: 150,657
Corporate Owned: 137,281
Aircraft Accident/Incident Report
Miami, Florida
Tuesady, October 26, 2010 21:30 EDT
NTSB Narrative Summary Released at Completion of Accident
Flight data recorder data revealed that, after takeoff from Miami International Airport (MIA), Miami, Florida, the airplane climbed for about 16 minutes and was passing through an altitude of approximately 32,000 feet when the rapid decompression occurred. The flight crew declared an emergency (the first officer was the pilot flying) and returned to MIA. Post accident examination of the airplane revealed fatigue cracking of the upper fuselage skin above the forward left passenger (L1) door. The fatigue cracking penetrated the fuselage skin, leading to a rupture and an approximate 18-inch-by-7-inch hole that depressurized the airplane.
NTSB examinations of a section of the fuselage crown skin (from body station 374 to body station 439) where the rupture occurred revealed fatigue cracking along the lower longitudinal step of the chemically milled pocket just above the stringer S-4L (left) lap joint. The fatigue cracking initiated on the interior surface of the skin at multiple locations and propagated through the skin thickness. The skin thickness at the base of the chemically milled step measured 0.035 to 0.037 inch—which is less than the 0.039-inch minimum thickness specified by Boeing. Calculations from an NTSB study of the fatigue striation density and propagation in the fatigue region indicate that it would take an average of 3,709 total cycles for a crack to grow through skin with 0.035-inch thickness and an average interval of 917 cycles for a crack to grow from a minimally detectable size and penetrate a 0.035-inch skin thickness.
The area of cracking and rupture on the accident airplane was not subject to any specific inspections, service bulletins (SB), or airworthiness directives (AD) at the time of the accident. Following the accident, on November 22, 2010, Boeing issued SB 757-53-0097, which called for repetitive external inspections (every 30, 200 cycles, or 300 hours depending on the inspection method) to detect cracks in the fuselage skin along the chemically milled step at stringers S-4L (left) and S 4R (right) between body station 297 and body station 439. On January 10, 2011, the Federal Aviation Administration issued AD 2011-01-15 (effective January 25, 2011) mandating the inspections recommended in SB 757-53-0097.
During its investigation, the NTSB learned of a United Airlines 757 and a second American Airlines 757 that exhibited cracking in the fuselage skin similar to the accident airplane; both had nonconforming thickness at the base of the chemically milled step at the stringer location specified in the SB. Records of manufacture for the skin panels on the accident airplane and the other airplanes with fuselage skin cracking were not retained, and were not required to be retained; therefore, a cause for the manufacturing nonconformance could not be identified.
NTSB Probable Cause Narrative
Fatigue failure of the fuselage crown skin due to incorrect manufacturing of the crown skin panel that resulted in a skin thickness less than the manufacturer-specified thickness.
Event Information
| Type of Event | Accident |
| Event Date | 10/26/2010 |
| Event Day of the Week | Tuesday |
| Time of Event | 2130 |
| Event Time Zone | Eastern Daylight Time |
| Event City | Miami |
| Event State | FLORIDA |
| Event Country | -- |
| Zipcode of the event site | -- |
| Event Date Year | 2010 |
| Event Date Month | 10 |
| MidAir Collision Indicator | No |
| On Ground Collision occurred ? | No |
| Event Location Latitude | -- |
| Event Location Longitude | -- |
| Event Location Airport | -- |
| Event Location Nearest Airport ID | MIA |
| Indicates whether the acc/inc occurred off or on an airport | Off Airport/Airstrip |
| Distance from airport in statute miles | -- |
| Degrees magnetic from airport | -- |
| Airport Elevation | -- |
| Weather Briefing Completeness | -- |
| Investigator's weather source | -- |
| 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 | -- |
| Lowest Ceiling Height | -- |
| Lowest Non-Ceiling Height | -- |
| Sky/Lowest/Cloud Conditions | -- |
| Sky Condition for Lowest Ceiling | -- |
| 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 | -- |
| 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 | 160 |
| Injury Total Serious | -- |
| Injury Total All | -- |
| Investigating Agency | NTSB |
| NTSB Docket Number (internal use) | -- |
| NTSB Notification Source | American Airlines |
| NTSB Notification Date | -- |
| NTSB Notification Time | -- |
| Fiche Number and/or location -used to find docket information | -- |
| Date of most recent change to record | Sep 19 2011 5:07PM |
| User who most recently changed record | schd |
| Basic weather conditions | -- |
| FAA District Office | -- |
Aircraft Involved |
|
|---|---|
Aircraft #1 |
|
| Aircraft Registration Number | N626AA |
| NTSB Number | DCA11FA004 |
| Missing Aircraft Indicator | -- |
| Federal Aviation Reg. Part | Part 121: Air Carrier |
| Type of Flight Plan filed | -- |
| Flight plan Was Activated? | -- |
| Damage | Substantial |
| Aircraft Fire | None |
| Aircraft Explosion | None |
| Aircraft Manufacturer's Full Name | BOEING |
| Aircraft Model | 757-223 |
| Aircraft Series Identifier | -- |
| Aircraft Serial Number | 24584 |
| Certified Max Gross Weight | -- |
| Aircraft Category | Airplane |
| Aircraft Registration Class | -- |
| Aircraft is a homebuilt? | No |
| Flight Crew Seats | 2 |
| Cabin Crew Seats | 4 |
| Passenger Seats | 154 |
| Total number of seats on the aircraft | 178 |
| Number of Engines | 2 |
| Fixed gear or retractable gear | Fixed |
| Aircraft, Type of Last Inspection | -- |
| Date of Last Inspection | -- |
| Airframe hours since last inspection | -- |
| Airframe Hours | 63010 |
| ELT Installed | Yes |
| ELT Activated | No |
| ELT Aided Location of Event Site | No |
| ELT Type | Unknown |
| Aircraft Owner Name | WILMINGTON TRUST COMPANY TRUSTEE |
| Aircraft Owner Street Address | RODNEY SQ NO CORP TR ADMIN |
| Aircraft Owner City | WILMINGTON |
| Aircraft Owner State | DE |
| Aircraft Owner Country | USA |
| Aircraft Owner Zipcode | 19890 |
| Operator is an individual? | No |
| Operator Name | AMERICAN AIRLINES INC |
| Operator Same as Owner? | No |
| Operator Is Doing Business As | -- |
| Operator Address Same as Owner? | No |
| Operator Street Address | -- |
| Operator City | -- |
| Operator State | -- |
| Operator Country | USA |
| Operator Zip code | -- |
| Operator Code | AALA |
| 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 | AALA025A |
| Indicates whether an air carrier operation was scheduled or not | Scheduled |
| Indicates Domestic or International Flight | Domestic |
| Operator carrying Pax/Cargo/Mail | Passenger Only |
| Type of Flying (Per_Bus / Primary) | -- |
| Second Pilot on Board | Yes |
| Departure Point Same as Event | -- |
| Departure Airport Code | -- |
| Departure City | -- |
| Departure State | -- |
| Departure Country | -- |
| Departure Time | -- |
| Departure Time Zone | -- |
| Destination Same as Local Flt | -- |
| Destination Airport Code | -- |
| Destination City | -- |
| Destination State | -- |
| Destination Country | -- |
| Specific Phase of Flight | -- |
| Report sent to ICAO? | -- |
| Evacuation occurred | -- |
| Date of most recent change to record | Aug 9 2011 10:59AM |
| User who most recently changed record | warl |
| Since inspection or accident | -- |
| Event Location Runway Number and Location | -- |
| Runway Length | -- |
| Runway Width | -- |
| Sight Seeing flight | No |
| Air Medical Flight | No |
| Medical Flight | -- |