Helicopter Sikorsky HO4S-3 Serial 55-609 Register 138524 used by US Navy USN. Built 1953. Aircraft history and location Aircraft History 138524 US Navy 1953-12-03Sikorsky S-55 c/n 55-609, ff:? del USN as HO4S-3, 138524, 03Dec53. Send Updates Use APP to upload photo @ (optional) When Now? / / Send