Helicopter Sikorsky H-19D Chickasaw Serial 55-998 Register 56-1520 used by US Army Aviation Army. Built 1956. Aircraft history and location Aircraft History 56-1520 US Army Aviation 1956-08-08Sikorsky S-55 c/n 55-998, ff:? del US Army as H-19D, 56-1520, 08Aug56. Send Updates Use APP to upload photo @ (optional) When Now? / / Send