ABSTRACT
Maintenance is an important element of the aviation industry worldwide, and in 1989 U.S. airlines spent around 12% of their operating costs on the maintenance activity [1, 2]. During the period from 1980 to 1988, the cost of airline maintenance increased from about $2.9 billion to $5.7 billion [3]. This increase is attributable to factors such as increase in air traffic and increased maintenance for continuing airworthiness of aging aircraft.
