The OH-58D (Bell Model 406) was the result of the Army Helicopter Improvement Program (AHIP). An upgraded transmission and engine gave the aircraft the power it needed for nap-of-the-earth flight profiles, and a four-bladed main rotor made it much quieter than the two-bladed OH-58C. The OH-58D introduced the distinctive Mast-Mounted Sight (MMS) above the rotor system, and a mixed glass cockpit, with traditional instruments identified as "standby" for emergency use.
The AH-58D was an OH-58D version operated by Task Force 118 (4th Squadron, 17th Cavalry) and modified with armament in support of Operation Prime Chance. The weapons and fire control systems would become the basis for the Kiowa Warrior. AH-58D is not an official DOD aircraft designation, but is used by the Army in reference to these aircraft. The Kiowa Warrior, sometimes referred to by its acronym KW, is the armed version of the OH-58D Kiowa. The main difference that distinguishes the Kiowa Warrior from the original AHIP aircraft is a universal weapons pylon found mounted on both sides of the aircraft. These pylons are capable of carrying combinations of AGM-114 Hellfire missiles, air-to-air Stinger (ATAS) missiles, 7-shot 2.75 inches (70 mm) Hydra-70 rocket pods, and an M296 .50 caliber machine gun. The standard of performance for aerial gunnery from an OH-58D is to achieve at least one hit out of 70 shots fired at a wheeled vehicle 800 to 1,200 m away. The Kiowa Warrior upgrade also includes improvements in available power, navigation, communication and survivability, as well as modifications to improve the aircraft's deployability.