Helicopter Sikorsky HO4S-3 Serial 55-606 Register 138521 used by US Navy USN. Built 1953. Aircraft history and location Aircraft History 138521 US Navy 1953-11-30Sikorsky S-55 c/n 55-606, ff:? del USN as HO4S-3, 138521, 30Nov53. Send Updates Use APP to upload photo @ (optional) When Now? / / Send
