Treating ailments of aging aircraft.

They are common complaints of getting old - fatigue, stiff joints, cracked skin, and damaged body parts in need of repair. Growing old can be just as debilitating for aircraft as it is for people, so Purdue University researchers are taking a holistic approach to understanding and treating aging in planes.

"Aging aircraft are a precious resource," indicates Alten F. Grandt, professor of aeronautics and astronautics. "Because of military cutbacks and the large replacement costs for commercial aircraft, it's become more common to operate planes beyond what used to be retirement age.

"Designers and manufacturers have been very successful in ensuring that planes are safe from damage caused by cracking and corrosion over a normal lifetime. But as we extend planes' operational lives, we have to reexamine these and other damage tolerance factors and how they apply to aging aircraft. It's a significant challenge to keep air operations reliable, safe, and economic."

Areas being studied include how cracks and corrosion form over time and how tiny cracks in an airplane's structure and skin grow and interact with larger ones. The researchers also are investigating possible treatments and preventatives for these airplane ailments, such as using composite materials to repair cracks. techniques to inhibit corrosion, and methods to help maintenance personnel more accurately assess structural damage.

Commercial jets are designed to be used for approximately 20 years, but the actual safe operating life depends on several factors in addition to age, including a plane's number and type of flights. maintenance procedures, and the environment in which it flies. Structural damage and failure - such as the...