Helicopter Sikorsky HO4S-3 Serial 55-703 Register 138594 used by US Navy USN. Built 1954. Aircraft history and location Aircraft History 138594 US Navy 1954-05-10Sikorsky S-55 c/n 55-703, ff:? del USN as HO4S-3, 138594, 10May54. Send Updates Use APP to upload photo @ (optional) When Now? / / Send