Helicopter Sikorsky HRS-1 Serial 55-057 Register 127821 used by US Marine Corps USMC. Built 1951. Aircraft history and location Aircraft History 127821 US Marine Corps 1951-09-05Sikorsky S-55 c/n 55-057, ff:? del USMC as HRS-1, 127821, 05Sep51 1958-02-21 soc 21feb58 San Diego Send Updates Use APP to upload photo @ (optional) When Now? / / Send