Apr 18 2011
Anthony Ingraffea, Cornell University professor of engineering, is an expert in structural aerospace engineering. His research concentrates on computer simulation and physical testing of complex fracturing processes.
Ingraffea comments on the recent news that the FAA has ordered very frequent inspections of Boeing 737 airplanes in the Southwest Airlines fleet.
He says:
"When Southwest Airlines found a large crack in a Boeing classic model 737 fuselage in early April, shockwaves moved through the airline industry. The fuselage cracks weren't supposed to happen so soon.
"In 1988, after the Aloha Airlines tragedy - engineers from NASA, the FAA, industry and academia set about learning the causes. This led to federal laws on aging aircraft. By 1993, after consulting with these many engineers, Boeing fixed the 737 aircraft and modified design for future models.
"Yet last week the Federal Aviation Administration issued an air-worthiness directive. The directive said that certain Boeing model 737 planes with more than 30,000 cycles [take-offs and landings], had to be inspected for fuselage cracks every 500 cycles - which is a few months of service. For the airlines, that's a substantial loss of revenue, due to a plane being grounded for inspection.
"The recent Southwest Boeing 737 plane had only 39,000 cycles and it was close to 15 years old. That's what makes this problem so shocking. The Boeing 737 plane involved in the Aloha tragedy had about 80,000 cycles. Boeing 737 airplanes used in U.S. domestic flights typically leave service after 60,000 cycles.
"Planes of advanced age are sometimes sold to international carriers, where fuselage cracks may not be examined or detected. For travelers flying on these international carriers: Buyer beware."