Beechcraft L - 23 Seminole The Beechcraft L - 23 Seminole ( later designated U - 8 ) was the United States Armed Forces designation for the Beechcraft Twin Bonanza and Queen Air aircraft in its inventory . Design and development . In 1951 the United States Army evaluated a Twin Bonanza at Fort Bragg , North Carolina and subsequently ordered four ' off - the - shelf ' Model 50s as YL - 23s , these being delivered in early 1952 . Further examples of the Model 50 were ordered under the designation L - 23A and Model B50s were also ordered under the designation L - 23B . These accounted for the majority of Twin Bonanza production during 1952 and 1953 , the first L - 23A being delivered in February 1953 and the last L - 23B being delivered in April the following year . , shortly before cessation of the Korean War . In 1955 the United States Air Force ordered a single Model C50 Twin Bonanza under the designation XL - 23C for evaluation ; this was the only L - 23 variant not delivered to the US Army as no further orders were placed by the Air Force . In 1956 deliveries of L - 23s to the Army recommenced when Beechcraft delivered six Model D50s under the designation L - 23E . In January 1957 the first example of the L - 23D was delivered , based on the Model E50 Twin Bonanza . During 1958 the remaining L - 23A and L - 23B aircraft in service ( a few had crashed ) were returned to the Beechcraft factory , where they were remanufactured to a similar standard as new - build L - 23Ds and then re - designated as such with new constructor ' s numbers and military serial numbers . In 1958 the Army also ordered 11 RL - 23Ds with further examples being converted from L - 23Ds . These aircraft featured belly - mounted radar , either AN / APS - 85 in a large pod or AN / APQ - 86 in a long narrow pod mounted on brackets with a modified nose as well . Also in 1958 Beechcraft began to develop a variant with a larger cabin at the request of the US Army . The L - 23F that emerged had the same wings and tail but up to ten people could now fit in the longer , wider and higher cabin compared to only five in earlier L - 23s . Beechcraft gave the type the in - house designation of Model 65 and developed it as a civilian aircraft as well , christening it the " Queen Air " . The first two Model 65s built were retained by Beechcraft as prototypes and the third was delivered to the Army in 1960 , with a further 23 being delivered that year and in 1961 . Operational history . The first L - 23As entered service in 1953 and the type served the US Army for almost forty years , the last U - 8Fs being retired in 1992 . When US military aircraft designations were revised in 1962 , the remaining L - 23D , RL - 23D , L - 23E and L - 23F aircraft became U - 8Ds , RU - 8Ds , U - 8Es and U - 8Fs . A further 47 Model 65s were ordered in 1962 and 1963 as U - 8Fs ; one of these was delivered to the Pakistan Army , the only delivery outside the US military ( although other nations bought Queen Airs as military aircraft ) . These were the final new - build aircraft in the series , however the unique Beechcraft Model 87 turboprop proof - of - concept aircraft used in developing the King Air was delivered to the Army as the NU - 8F in 1964 ( this was later re - designated the YU - 21 ) and a few used Queen Airs were also taken by the Army . Many U - 8Fs were modified during their service lives to a similar standard as civilian Excalibur Queen Airs . The most obvious modifications are more powerful Lycoming IO - 720 eight - cylinder engines in place of the factory - fitted six - cylinder engines ; and bulged main landing gear doors that fully enclose the wheels when the gear is retracted instead of the wheels partially protruding through the doors . Many L - 23Ds / U - 8Ds and U - 8Fs have been registered as civilian aircraft since retirement from military service .