Helicopter Sikorsky H-19A Chickasaw Serial 55-170 Register 51-3891 used by US Air Force USAF. Built 1952. Aircraft history and location Aircraft History 51-3891 US Air Force 1952-06-24Sikorsky S-55 c/n 55-170, ff:? del USAF as H-19A, 51-3891, 24Jun52. Send Updates Use APP to upload photo @ (optional) When Now? / / Send