Boeing's chief 737 engineer said Boeing was surprised to see that the roof of a Southwest Airlines jetliner ripped open during a flight last week on its way to Sacramento.
The incident disrupted Southwest flights from coast to coast all weekend and into Monday. Dozens of Bay Area flights were cancelled or delayed because of emergency inspections of all 737 planes in the Southwest fleet. Flight did not get back to normal until Tuesday.
Engineer Paul Richter said in a conference call, which included he Associated Press, that Boeing did not expect to see wear in the middle section of the fuselage until the plane involved was much older.
Boeing said when the company designed the 737-300, it expected the skin joint that failed to be robust enough not to require inspections for at least 60,000 pressurization cycles. The Southwest jet that needed to make an emergency landing Friday had less than 40,000 cycles.
Pressurization cycles are the number of times a plane takes off and lands. .
Southwest pulled nearly 80 planes for inspections and found five with similar cracks. Richter told AP Tuesday that Boeing gave Southwest instructions on how to repair the cracks on three of those planes.
On Tuesday the FAA ordered inspection of all 737 planes worldwide. Most of the planes in the United States were Southwest airplanes that had already been inspected.