The BO105 series are still the toughest helicopter man has made and the 'genus' of the twin engine Helicopter. It was designed by the Germans and like all things they build - built well, built to perform and made with quality. Take five minutes to compare side by side the BO105 and the BK117 and you will see the BO105's DNA all over the BK117 rotor system and likewise many other components. There are a few variants of BO105 but the two most prevalent are the CBS4 and the CBS5, where the key difference is the Main Rotor Blades. The CBS5 blades with their tapered ends afford you another 150 kg's Max All Up Weight [MAUW] when One Engine Inoperative. Your limitation MAUW doesn't change, it is still 2500 kg's but if the other engine quits you can be a little bit heavier and get good performance. The caveat [i.e less than ideal feature...] about the CBS5 blades is that they cost you $50,000 EURO each! You can buy an entire set of four MR Blades for the CBS4 for $50,000 USD and the best thing is they run on-condition. The message here is that we are experts on the maintenance and operation of the BO105's, we have overhauled a dozen BO105's and shipped them to happy clients around the world.