Helicopter Sikorsky HRS-1 Serial 55-028 Register 127794 used by US Marine Corps USMC. Built 1951. Aircraft history and location Aircraft History 127794 US Marine Corps 1951-06-02Sikorsky S-55 c/n 55-028, ff:? del USMC as HRS-1, 127794, 02Jun51 1955-07-20 20jul55 dbr Send Updates Use APP to upload photo @ (optional) When Now? / / Send