Long-haul aircraft tend to be the highest total time due to average stage length. Consider that decent utilization on a 747 or other long-haul heavy may be 14-16 hours per day, so the total time adds up fast. Also it's very few cycles due to the long legs, and cycle count is what most affects airframe fatigue. Where a 747 may be in flight for 15 hours a day flying only one or two legs, a 737 or RJ may only fly 8 hours, but log 10-12 cycles. While some components such as engines can be time limited, many components like landing gear and even the pressure vessel can be cycle limited..
..CT
