High availability of aircraft is crucial for airline operator profit-
ability. Therefore, defective components are replaced by compo-
nents in good condition during line maintenance, instead of being
repaired inside the aircraft. The defective component is then
repaired separately, allowing operators to reduce the duration of
line maintenance. Independent repair shops perform these repairs
on a commercial basis. Component repairs (non-military) gener-
ated a turnover of $9 billion in recent years [4].