Helicopter Sikorsky HR2S-1 Serial 56-003 Register 138420 used by US Marine Corps USMC. Built 1956. Aircraft history and location Aircraft History 138420 US Marine Corps 1956-04-18Sikorsky S-56, c/n 56-003, ff:? del US Marine Corps as HR2S-1, 138420, 18Apr56 soc & scr unk. 1959-07-20 soc 20jul59 Send Updates Use APP to upload photo @ (optional) When Now? / / Send