Helicopter Sikorsky H-19D Chickasaw Serial 55-987 Register 55-4939 used by US Army Aviation Army. Built 1956. Aircraft history and location Aircraft History 55-4939 US Army Aviation 1956-07-24Sikorsky S-55 c/n 55-987, ff:? del US Army as H-19D, 55-4939, 24Jul56. Send Updates Use APP to upload photo @ (optional) When Now? / / Send