Helicopter Sikorsky HO4S-3 Serial 55-626 Register 138526 used by US Navy USN. Built 1954. Aircraft history and location Aircraft History 138526 US Navy 1954-01-05Sikorsky S-55 c/n 55-626, ff:? del USN as HO4S-3, 138526, 05Jan54. Send Updates Use APP to upload photo @ (optional) When Now? / / Send