Tucumseh,
May I also add the muddying of water caused by using COTS (components off the shelf) which was encouraged by our lords and masters in order to save money - however this has made the configuration of aircraft within a fleet nearly impossible to manage... it has been suggested that a new installation in a COTS fleet has to be fully tested for every aircraft because the configuration for each aircraft (if known) is different. This is particularly problematical for complex aircraft - especially when fitted with highly classified equipment and software.