Helicopter Sikorsky H-19D Chickasaw Serial 55-1006 Register 56-1521 used by US Army Aviation Army. Built 1956. Aircraft history and location Aircraft History 56-1521 US Army Aviation 1956-09-12Sikorsky S-55 c/n 55-1006, ff:? del US Army as H-19D, 56-1521, 12Sep56. Send Updates Use APP to upload photo @ (optional) When Now? / / Send