Monday, April 4, 2011
Experts say cracks are a fact of of flying with aging aircraft, particularly those which get pressurized and depressurized with each flight.
"The short airplanes, the 737s, that have many, many take offs and landings in a day...they pressurize, unpressurized, pressurize, unpressurized. It works just like bending a paper clip back and forth, back and forth. Eventually you wear it out. And that's what's happening to these airplanes," Melinda Laubach-Hock, Aging Aircraft Laboratory Director, National Institute for Aviation Research (NIAR), said.
Trying to predict when planes will break is one of the challenges facing engineers on the WSU campus. The aging aircraft lab is part of the National Institute for Aviation Research.
"We take these older airplanes. We take them apart. We look for what we call precursors to damage...small cracks, corrosion, things that exist on a lot of airplanes but aren't dangerous to the airplane. But those give us a prediction for what's going to happen in the future," Laubach-Hock added.
From those findings, WSU's NIAR develop repair techniques and inspection plans for the air frames.
It was 1988 when the fuselage of an Aloha 737 ripped open, killing one person. The airline industry and safety officials started taking a keener interest in airplane fatigue factors after that.
"The problem has continued to plague basically every airplane out there," Lauback-Hock said. She says determining when to retire an airplane depends a lot on how it is used. "It's just like a car. At some time your car's going to start wearing out. Unfortunately, with airplanes, we see that at 30,000 feet instead of sitting on the ground when something goes wrong with your car," she said. "I think we need to realize that at some point these airplanes have reached as long as they can fly."