Stress
April 06, 2011, 12:50 AM
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Joan Lowy reports in the Atlanta Journal-Constitution on something that caught my eye for personal reasons:

Southwest grounded nearly 80 Boeing 737-300s after its jet leaving Phoenix lost pressure Friday, forcing pilots to make an emergency landing 125 miles away in Yuma.

Friday's incident, however, raised questions about the impact that frequent takeoffs and landings by short-haul carriers like Southwest put on their aircraft and the adequacy of the inspections.

Cracks can develop from the constant cycle of pressurizing the cabin for flight, and releasing it.

Since there had been no previous accidents or major incidents involving metal fatigue in the middle part of the fuselage, Boeing maintenance procedures called only for airlines to perform a visual inspection.

But airlines, manufacturers and federal regulators have known since at least 1988 that planes can suffer microscopic fractures. That year, an 18-foot section of the upper cabin of an Aloha Airlines 737-200 peeled away in flight, sucking out a flight attendant. ...

Southwest appeared eager Monday to shift blame to Boeing. The airline said it had never been alerted to a potential problem where overlapping panels of aluminum skin are riveted together on the 737-300.

"This is a Boeing-designed airplane. This is a Boeing-produced airplane," Southwest spokeswoman Linda Rutherford said. "It's obviously concerning to us that we're finding skin-fatigue issues."

I put this up because this is a lot of what my Dad, now 94, did during his four decades as a stress engineer at Lockheed: stare at pictures of microscopic cracks in airplane metal and try to figure out whether to tell the airline or the Air Force, "You know, funny thing, this plane turns out not to be quite as safe as we told you it would be when you bought it from us, so you'd better ground this expensive asset while we work out an expensive fix," or, "No problemo! No way is this plane going to rip apart in flight, sending everyone on board plunging to their deaths. Trust us."

Aeronautical stress engineering is a stressful job.