Helicopter Sikorsky H-19B Chickasaw Serial 55-391 Register 51-3925 used by US Air Force USAF. Built 1953. Aircraft history and location Aircraft History 51-3925 US Air Force 1953-04-20Sikorsky S-55 c/n 55-391, ff:? del USAF as H-19B, 51-3925, 20Apr53. Send Updates Use APP to upload photo @ (optional) When Now? / / Send