A National Transportation Safety Board (NTSB) report released Friday blamed bad workmanship at Boeing for a 2011 incident when a five-foot-long hole ripped open in the roof of a 737-300 during a Southwest Airlines flight.
When the jet was assembled 15 years earlier, the drilling of the rivet holes along one side of the fuselage skin panel that tore away “showed a lack of attention to detail and extremely poor manufacturing technique,” the report concluded.
The work also “was not in accordance with Boeing specifications or standard manufacturing practices.”
The NTSB said evidence indicates the hidden cracks emanating from the rivet holes had been slowly growing with each takeoff and landing, and had started “approximately when the airplane entered service” in 1996.
However, the safety agency’s report suggests this may have been a one-off error by a mechanic.
In a statement, Boeing pointed to the NTSB finding that subsequent inspections of other 737s found no similar damage in the same fuselage panel joints.
The NTSB concluded that therefore it’s “unlikely that there was a systemic QA (quality assurance) error at the Boeing facilities.”
The report reveals that a panel above the one that ripped away was replaced at some late stage of the assembly process and that the join between these two panels — three rows of rivet holes along the overlap — showed serious discrepancies including non-circular holes, double-drilled holes, gaps between the rivets and the holes, and metal burrs protruding from under the rivets.
Read more here: http://seattletimes.com
http://www.ntsb.gov/doclib/reports/2013/AAB1302.pdf
NTSB Identification: DCA11MA039
Scheduled 14 CFR Part 121: Air Carrier operation of SOUTHWEST AIRLINES CO
Accident occurred Friday, April 01, 2011 in Yuma, AZ
Aircraft: BOEING 737, registration: N632SW
Injuries: 1 Minor,121 Uninjured.
This is preliminary information, subject to change, and may contain errors. Any errors in this report will be corrected when the final report has been completed. NTSB investigators traveled in support of this investigation and used data obtained from various sources to prepare this aircraft accident report.
On April 1, 2011, at about 1557 mountain standard time (MST), Southwest Airlines flight 812, a Boeing 737-300, registration N632SW, experienced rapid depressurization at approximately 34,000 feet. The flight crew conducted an emergency descent and diverted to Yuma, Arizona. Upon landing, a 5-foot x 1-foot hole in the crown area was observed on the left side of the airplane, aft of the over-wing exit at the stringer 4L lap joint. Of the 117 passengers and 5 crew members onboard, one flight attendant received a minor injury. The flight was being conducted under 49 Code of Federal Regulations Part 121 as a regularly scheduled passenger flight between Phoenix Sky Harbor International Airport, Phoenix, Arizona and Sacramento International Airport, Sacramento, California.
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