Some aircraft are modified with surveillance systems for various missions, including the Cefly Lancer, Beechcraft RC-12 Guardrail and Project Liberty programs.The aircraft was essentially an "off-the-shelf" Super King Air 200, powered by the type's standard Pratt & Whitney Canada PT6A-41 engines.For that variant, Beechcraft built the basic plane and then sent it to Greenville, Texas where sophisticated intelligence, surveillance and reconnaissance (ISR) equipment was installed by L-3 Communications Missions Integration.With its roles taken over by the growing MQ-9 Reaper fleet, the Air Force decided to divest itself of the 41 Liberty aircraft and turn them over to the U.S. Army and U.S. Special Operations Command, which was completed by October 2015.The following RC-12 variants, although similar to earlier RC-12s based on the King Air 200, represent specially built airframes that[citation needed] combined upgraded engines (1,100 shp PT6A-67) and structural upgrades (swapping the traditional KA-200/300/350 T-Tail for the 1900 modified T-Tail to compensate for torque and aerodynamics and having reinforced spars to compensate for the increased maximum gross weight[citation needed] - up to as high as 16,500 lbs).[citation needed] Note: The U.S. military also operates other King Air versions under other designations, including the C-6 Ute and T-44 series.