Contaminates on the insulators of an electrical power line can cause an electrical fault and must be periodically cleaned and maintained. An Air2 helicopter is used to haul 300 liters of purified water to the high voltage transmission line, then uses a custom built 18 foot insulated washing boom to clean the insulators. The helicopter in this video is cleaning an energized 500 kV transmission line.

Air2 Hot Washing Electrical Power Line Insulators