Helicopter Sikorsky HO4S-3 Serial 55-526 Register 138497 used by US Navy USN. Built 1953. Aircraft history and location Aircraft History 138497 US Navy 1953-09-03Sikorsky S-55 c/n 55-526, ff:? del USN as HO4S-3, 138497, 03Sep53. soc Send Updates Use APP to upload photo @ (optional) When Now? / / Send