The repair itself is not such a big deal, all you need is the window itself, sealant, two trained mechanics, a hangar and enough time to take the old one out, remove the old sealant, put the new one in it's place (into the sticky sealant), let the stuff dry, do the paperwork and send the aircraft off. Keeps two people entertained for a normal shift. I would not want to do it in a dark and stormy night in the middle of nowhere under a tree!