The Bell OH-58 Kiowa is a family of single-engine single-rotor military helicopters used for observation, utility, and direct fire support. It was produced by the American manufacturer Bell Helicopter and is closely related to the Model 206A JetRanger civilian helicopter. The OH-58 was originally developed during the early 1960s as the D-250 for the Light Observation Helicopter (LOH). While the rival Hughes OH-6 Cayuse was picked over Bell's submission in May 1965, the company refined its design to create the Model 206A, a variant of which it successfully submitted to the reopened LOH competition two years later. The initial model, designated by the service as the OH-58A, was introduced in May 1969. Successive models would follow, often with uprated engines, enhanced protection systems, and other improvements, cumulating in the OH-58F. Additional improvements, such as the OH-58X, were proposed but ultimately not pursued. During the 1970s, the US Army became interested in pursuing an advanced scout helicopter, for which the OH-58 would be further developed, evaluated, and ultimately procured as the OH-58D Kiowa Warrior. The OH-58D is equipped to perform armed reconnaissance missions and to provide fire support to friendly ground forces; it is equipped with a distinctive Mast Mounted Sight (MMS) containing various sensors for target acquisition and laser designation. Another visible feature present on most OH-58s are knife-like extensions above and below the cockpit that form part of the passive wire strike protection system. While early-build OH-58s were equipped with a two-bladed main rotor, from the OH-58D onwards, a four-bladed counterpart was used instead. The OH-58 was primarily produced for the United States Army. Only two months after the type's entry to service, it was first deployed into the Vietnam War. The US Army would make extensive use of various OH-58 models across numerous warzones over the decades, seeing active combat during the Gulf War, the Invasion of Panama, and the War in Afghanistan amongst others. During 2017, the US Army opted to withdraw its remaining OH-58s and replace them with newer rotorcraft, such as the Boeing AH-64 Apache and Eurocopter UH-72 Lakota, as well as increasing use of unmanned aerial vehicles (UAVs). Furthermore, the OH-58 has been exported to Austria, Canada, Croatia, the Dominican Republic, Taiwan, Saudi Arabia, and Greece. It has also been produced under license in Australia. Development Light Observation Helicopter (LOH) On 14 October 1960, the United States Navy approached 25 helicopter manufacturers to request