Keeping


transmission lines in shape


The TVA fleet spends much of its time making sure that 16,000- plus miles of transmission lines remain 99.999 percent reliable. By law they must check the entire system at least every three years. They inspect rights-of-way annually to make sure lines are clear of vegetation.


“Reliability is one of the driving factors for new industry to come in and build here,” Hammond said. “We’re always using helicopters for routine maintenance, construction, and inspection,” Featherston added.


TVA pilots and linemen can cover about 200 miles of line per day during inspections. If they see a problem during inspections, they call in a ground crew and keep flying. They can go two hours before


refueling. One of the most common repairs is replacing cotter keys that back out of screws holding insulators on towers. The keys can loosen up after a few years of vibrating in windy conditions. Linemen also are on the lookout for the aforementioned buzzard droppings, which can cause insulators to conduct electricity instead of insulating it.


Flight crews use LIDAR for about a week of each month for the ROW inspections, measuring the distance between tree branches and towers and measuring how much lines are sagging. They also use LIDAR and piezometers to check coal ash storage for safety. Infrared instruments seek out transmission line hot spots caused by lightning strikes and other issues.


TVA’s MD 530F works on a long-line operation supporting linemen in a crane bucket. rotorcraftpro.com 55


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