Helicopter Sikorsky XHR2S-1 Serial 56-3X Register 133733 used by US Marine Corps USMC. Built 1954. Aircraft history and location Aircraft History 133733 US Marine Corps 1954-02-26Sikorsky S-56, cn 56-3X, ff:? del NPRO as XHR2S-1, 133733, 26Feb54 xfer HMX-1, MCAS Quantico, VA, 1956 scr unk. HMX-1 Send Updates Use APP to upload photo @ (optional) When Now? / / Send