Boeing 737 N387SW

Summary

On 13 July 2009 at about 21:45 local time, a Boeing 737 registered N387SW, operated by Southwest Airlines Co, was involved in an accident near Charleston, West Virginia, United States. 131 people were on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

13 July 2009 at 21:45

Classification

Accident

Location

Charleston, West Virginia, United States

Nearest airport

Yeager Airport, Charleston, WV (CRW)

Coordinates

38.3731, -81.5931

Aircraft

Boeing 737

Registration

N387SW

Category

Airplane

Engines

2

Operator

Southwest Airlines Co

Operating rule

Part 121: Air Carrier

Phase of flight

Not recorded

Route

Nashville → Baltimore

Aircraft damage

Substantial

NTSB number

DCA09FA065

Nobody was injured.

Fuselage skin failure due to preexisting fatigue at a chemically milled step.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

Flight data recorder data revealed that the airplane took off and climbed for about 25 minutes to an altitude of approximately 35,000 feet, at which point the cabin altitude warning activated, and the captain disengaged the autopilot. Postincident examination of the airplane revealed fatigue cracking of the fuselage skin near the leading edge of the vertical stabilizer adjacent to the rupture. The fatigue cracking penetrated the fuselage skin and created an approximate 18-inch by 12-inch flap in the skin that depressurized the airplane. The fuselage skin assembly near the leading edge of the vertical stabilizer was manufactured by bonding two full aluminum sheets together, then selectively chemically milling away pockets (bays) of the inner sheet. Continuous fatigue cracks initiated from multiple origins on the inner surface of the skin adjacent to the step formed at the edge of the chemically milled area and propagated outward. Following the Southwest Airlines (SWA) flight 2294 event, on September 3, 2009, Boeing issued Service Bulletin (SB) 737-53A1301, calling for repetitive external inspections to detect cracks in the fuselage skin along the chemically milled step at stringers S-1 and S-2 right and between BS 827 and BS 847. (The hole from the SWA event was within those boundaries.) If cracks are detected, operators are to contact Boeing for repair instructions. On January 12, 2010, the Federal Aviation Administration issued Airworthiness Directive 2010-01-09, which mandated the inspection requirements in SB 737-53A1301.

Quoted verbatim from the NTSB record.