Helicopter Sikorsky H-19D Chickasaw Serial 55-1100 Register 56-1566 used by US Army Aviation Army. Built 1957. Aircraft history and location Aircraft History 56-1566 US Army Aviation 1957-07-23Sikorsky S-55 c/n 55-1100, ff:? del US Army as H-19D, 56-1566, 23Jul57. Send Updates Use APP to upload photo @ (optional) When Now? / / Send