Helicopter Sikorsky S-55 Serial 55-745 Register HS-2 used by Royal Thai Air Force. Built 1954. Aircraft history and location Aircraft History For HS-2 see also mi-8t 133 02 HS-2 Royal Thai Air Force 1954-06-29Sikorsky S-55 c/n 55-745, ff:? del RTAF as HS-2, 29Jun54. H3-2/97 Send Updates Use APP to upload photo @ (optional) When Now? / / Send