SEATTLE – A National Transportation Safety Board report released Friday blamed bad workmanship for a 2011 incident when a 5-foot-long hole ripped open in the roof of a Boeing 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 take-off and landing, and had started “approximately when the airplane entered service” in 1996. But 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.”
At the time, the inflight incident raised concern that aging jets might be more susceptible to metal fatigue cracking sooner in their life cycle than previously believed. Hans Weber, an aviation technical expert, president of Tecop International in San Diego, said the NTSB analysis dispels that concern.
“The workmanship was just terrible,” Weber said. “This has nothing to do with a typical fatigue fracture due to aging.
“I’m relieved that it’s not because of some aging process we didn’t understand,” he added.
On April 1, 2011, as Southwest Flight 812 climbed to 34,000 feet out of Phoenix with five crew members and 117 passengers aboard en route to Sacramento, Calif., the cracks finally opened into an 8-inch-wide gash in the jet’s ceiling.
Air rushed from the passenger cabin, and the rapid decompression caused an immediate loss of oxygen. As oxygen masks deployed, the pilots declared an emergency and descended quickly.
They landed safely in Yuma, Ariz.