Helicopter Sikorsky HRS-3 Serial 55-448 Register 137839 used by US Navy USN. Built 1953. Aircraft history and location Aircraft History 137839 US Navy 1953-06-04Sikorsky S-55 c/n 55-448, ff:? del USN as HRS-3, 137839, 04Jun53. Send Updates Use APP to upload photo @ (optional) When Now? / / Send