Helicopter Sikorsky H-19B Chickasaw Serial 55-418 Register 51-3939 used by US Air Force USAF. Built 1953. Aircraft history and location Aircraft History 51-3939 US Air Force 1953-05-13Sikorsky S-55 c/n 55-418, ff:? del USAF as H-19B, 51-3939, 13May53. Send Updates Use APP to upload photo @ (optional) When Now? / / Send