Helicopter Sikorsky CH-3C Serial 61-595 Register 66-13295 used by US Air Force USAF. Aircraft history and location Aircraft History 66-13295 US Air Force 1968-05-23 Sikorsky CH-3E USAF 21st SOS (56 SOW) w/o 23may68 crashed near Khe Sanh, Quang Tri Province, South Vietnam. 6 fatalities 21st SOS Send Updates Use APP to upload photo @ (optional) When Now? / / Send