Detailed history and photos of helicopter Sikorsky HO4S-3 Serial 55-686 Register 138590 used by US Navy USN Track service timeline and current status. Aircraft History 138590 US Navy 1954-05-10Sikorsky S-55 c/n 55-686, ff:? del USN as HO4S-3, 138590, 10May54. Send Updates Use APP to upload photo @ (optional) When Now? / / Send
