Boeing Says 737 Jet Cracking Happened Earlier Than Expected
737 Inspections
Kim White/Bloomberg
Boeing Co. said that metal fatigue inspections must be stepped up on older 737s after cracks developed earlier than expected on a Southwest Airlines Co. plane last week.
Boeing Co. said that metal fatigue inspections must be stepped up on older 737s after cracks developed earlier than expected on a Southwest Airlines Co. plane last week. Photographer: Kim White/Bloomberg
April 4 (Bloomberg) -- Aaron Kwittken, chief executive officer of Kwittken & Co., talks about Southwest Airlines Co.'s strategy after one of its Boeing Co. 737 jets split open during a flight last week, prompting an emergency landing. He speaks with Pimm Fox on Bloomberg Television's "Taking Stock." (Source: Bloomberg)
Boeing Co. (BA) said metal-fatigue inspections must be stepped up on older 737s, the world’s most widely flown jet, after cracks developed earlier than expected on a Southwest Airlines Co. (LUV) plane that split open last week.
Cracks on the so-called 737 Classic weren’t forecast to occur until “much later,” after 60,000 takeoff-and-landing cycles, Paul Richter, Boeing’s chief project engineer for older jets, said today on a conference call. The plane that ripped in an April 1 flight above Arizona had flown 39,781 cycles.
“We are all concerned about this recent development,” Richter said. He said Boeing is working with airlines worldwide to ensure that those making frequent, shorter flights, like Southwest, inspect the jets within five days.
The U.S. Federal Aviation Administration said today it will require inspections for cracks on all 737-300s, 737-400s and 737-500s that have flown more than 30,000 cycles, covering about 175 planes worldwide. The FAA also is taking the rare step of requiring checks again every 500 cycles as a precaution while the probe continues, Richter said.
Southwest, the biggest 737 operator, pulled 79 planes from service after the April 1 incident forced an emergency landing in Arizona. The Dallas-based carrier found cracks on five additional 737s, and Boeing has come up with repair plans for three of those so far, Richter said.
Southwest declined to comment on Boeing’s findings, said Brandy King, a spokeswoman for the Dallas-based carrier. The airline said it operated a full flight schedule today.
Fuselage Fasteners
Boeing, based in Chicago, was aware of the potential for problems with fatigue around the fasteners that hold the 737 fuselage panels together and changed the design for newer models of the plane starting in 2000, Richter said.
Boeing is urging airlines around the world to inspect the lower row of fasteners in the lap joints along the left and right side of the crown of the planes, a section about 50 feet long, Richter said. With two inspectors, one for each side, each check will probably take about eight hours, he said.
The company has “very high confidence” in the inspection technique with handheld instruments that can find “very short cracks” using electromagnetic technology, Richter said.
The FAA’s directive eventually will require about 570 planes to be checked, Richter said. Airlines that find cracks will need to collaborate with Boeing on how best to fix their aircraft, and will probably need to cut out and replace sections of the fuselage, he said.
Lap Joints
The Southwest repairs will probably require removing an 18- inch length of the lap joints and will take 8 to 16 hours per jet, he said.
The April 1 incident was “a statistical event” and doesn’t have anything to do with Southwest’s maintenance program or with how the carrier operates its planes, Richter said.
Boeing knew that the first 737s, which the company began building in Seattle in 1967, would have problems along the lap joints, and the FAA already has devised inspections and repairs for those planes, Richter said. The company changed the design for all 737-300s, -400s and -500s built after 1993, and those are the ones that weren’t expected to start cracking until they reached 60,000 cycles.
By 2000, when the models known as Next-Generation 737s began to be built, the company had developed a new design that’s “significantly different and much improved,” Richter said. Engineers were able to reduce how much the metal fuselage bends when the plane is pressurized as it ascends, he said.
Boeing has built more than 6,000 737s. The single-aisle jet, along with Airbus SAS’s A320, is the backbone of the aviation industry, used chiefly on domestic and short-haul flights.
After Southwest, the biggest operators of 737 Classics are Germany’s Deutsche Lufthansa AG (LHA), US Airways Group Inc. (LCC), Malaysia Airline System Bhd. and United Continental Holdings Inc. (UAL), according to data from aviation research firm Ascend.
To contact the reporter on this story: Susanna Ray in Seattle at sray7@bloomberg.net
To contact the editor responsible for this story: Ed Dufner at edufner@bloomberg.net
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