CH-47 Chinooks in Afghanistan Demonstrating the “Halo Effect,” Officially Known as the “Kopp-Etchells Effect” - When Sand and Dust Hit a Rapidly-Spinning Rotor.
Sand and dust hitting a spinning helicopter rotor can cause erosion, leading to the addition of titanium or nickel abrasion strips to the leading edge of the rotor to minimize the effect. The pyphoric oxidation of eroded particles from these strips cause the “halo.”
The Kopp-Etchells Effect is named after US Army Ranger Benjamin Kopp and British Army soldier Joseph Etchells, both of whom were killed in action in Afghanistan in 2009.
Hind Heist: Mount Hope III - 1987 CIA/Air Force Mission to “Acquire” an Abandoned Libyan Mi-24D Hind Helicopter in Chad
The 160th Special Operations Group, the “Night Stalkers,” used CH-47 Chinooks to recover a Mil Mi-24D Hind helicopter left behind by Libyan forces at a base within Chad during the border war between the two nations. The recovery team kept clear of nearby Libyan forces and endured a sandstorm to sweep in and recover the helicopter for intelligence purposes.