This NTSB report states that the Southwest crew’s emergency descent of WN 812 was “section of fuselage skin about 60 inches long by 8 inches wide had fractured and flapped open on the upper left side above the wing.” After extensive analysis of the metal section at issue (there was some question that the failure may be attributable to aging), it was categorically determined that the probable cause was as follows:
“The National Transportation Safety Board determines that the probable cause of this accident was the improper installation of the fuselage crown skin panel at the S-4L lap joint during the manufacturing process, which resulted in multiple site damage fatigue cracking and eventual failure of the lower skin panel.” (emphasis added)
Boeing is a company with a long record of excellence. The Safety Board is not infallible and maybe there is some other reason for this failure, but this appears to be very disturbing news.
The NTSB report indicates that Boeing issued an Alert Service Bulletin to all operators of specified line numbered B-737s. While that’s useful, some external indication that the company’s internal QC/QA and SMS programs have been reemphasized would be more reassuring. Boeing’s quality control performance has recently been subject to a major FAA enforcement sanction.
Whether public or not, internal responses to these problems need to be aggressive and comprehensive to reach from the line manufacturing personnel to the executives.Share this article: