 After evaluating the Sioux Scout in early 1964, the Army was impressed, but also felt the Sioux Scout was undersized, underpowered, and generally not suited for practical use.Later in 1964, the Army requested proposals for its Advanced Aerial Fire Support System (AAFSS).Bell proposed the D-262, a smaller version of the D-255, making better use of the T53 engine from the UH-1.