Detailed history and photos of helicopter Sikorsky HO4S-3 Serial 55-551 Register 138504 used by US Navy USN Track service timeline and current status. Aircraft History 138504 US Navy 1953-10-22Sikorsky S-55 c/n 55-551, ff:? del USN as HO4S-3, 138504, 22Oct53. Send Updates Use APP to upload photo @ (optional) When Now? / / Send
