Helicopter Sikorsky HO4S-3 Serial 55-625 Register 138525 used by US Navy USN. Built 1954. Aircraft history and location Aircraft History 138525 US Navy 1954-01-05Sikorsky S-55 c/n 55-625, ff:? del USN as HO4S-3, 138525, 05Jan54. Send Updates Use APP to upload photo @ (optional) When Now? / / Send