Watched a Vertol heli-logging in BC . The machine once flew in the North Sea . Columbia helicopters had been operating it safely without incident for thousands of hours . Their secret ? The first thing they did when they got it was switch out the gear boxes for the military version gearbox . And voila a safe hard working machine . That was twenty five years ago not sure if it is still heli logging today . They said they did not like the fancy civilian gearbox and the military version was better suited to their requirements. Who knew a gearbox is so important ?