HH-60G/MH-60G Pave Hawk
Block 152 Upgraded Communication, Navigation/Integrated Electronic Warfare (UCN/IEW)
The Block 152 upgrade, formally known as Upgraded Communication, Navigation/Integrated Electronic Warfare (UCN/IEW), was the most significant upgrade for the HH-60G/MH-60G Pave Hawk when it was introduced. The upgrades were designed to greatly enhance the aircraft's performance in locating and retrieving downed pilots from hostile territory. The program was managed by Aeronautical Systems Center (ASC). The combined government team included ASC, Warner Robins Air Logistics Center, and Air Combat Command.
New features included as part of the upgrade were an enhanced communication and navigation system and an electronic warfare suite that dispensed countermeasures to thwart missile and radar threats. These systems were integrated into a 1553 computer data bus, designed to greatly reduce aircrew workload. The 1553 data bus concept was developed in the late 1970s by Air Force personnel in the Avionics Laboratory, which subsequently became Sensors Directorate of Air Force Research Laboratory. The aircraft also featured a new, external, gun-mount system that supported a .50 caliber machine gun in addition to the existing 7.62mm "Minigun" or M240 machine gun options.
The Block 152 acquisition program started out as a series minor modification, fitting the new items in available space, but ended up as a major modification program with the relocation of almost every avionics unit. All of the communications and navigation information on the new aircraft were available on a single, control display unit. Another modification to the helicopter was the relocation of the forward-looking, infrared radar (FLIR) turret from an area that was below the nose and slightly to the left of the centerline, to an area on the nose that was higher off the ground along the centerline of the aircraft. This was primarily a maintenance-driven requirement. These aircraft had to land in unimproved areas, and there was a problem with these costly turrets being crushed, leading to the move of the turret up and forward.
Guns on the modified Pave Hawk were mounted externally, instead of being hinged to swing inside the cabin to lock in place, as part of either the A/A49-13 (7.62mm "Minigun") or A/A49E-14 (.50 caliber GAU-21/A) armament systems. This arrangement provided flight engineers, who operate the aircraft's weapons, with the advantage of closing the gunner's windows when flying in subzero temperatures, and freeing up cabin space. The guns locked in a fixed, forward-firing position. In this configuration, the capability existed for pilots to operate the weapons. The new mounts provided a weapon system that was completely external, to include the ammunition cans. The new system supported operation of the GAU-21/A .50 caliber machine gun. Previously, such a weapon could only be operated from the open door of the aircraft. Tests with such weapons had revealed stability issues, as well as making ingress and egress into the main cabin more difficult.
As another defensive measure, the new Pave Hawks would come equipped with electronic countermeasures that detect enemy radar and missile threats. The aircraft was designed to dispense flare and chaff automatically when these threats were detected. These flare-and-chaff buckets, never operationally certified before on any combat search-and-rescue helicopter, could operate in an automatic, semi-automatic or manual mode.
The communications, navigation and electronic warfare systems were integrated into an additional 1553 data bus. All of the aircraft's avionics, communications, navigation and electronic warfare systems fit into 2, floor-to-ceiling racks immediately behind the cockpit, next to the flight engineer and gunners' stations. The placement of these racks came as the result of a solution to a problem the team encountered when designing the new features. Originally the equipment was to be placed in the aft section of the aircraft. However, the weight of racks created a 400-pound, center-of-gravity problem. Placing 2 racks forward was the solution. Moving the FLIR turret forward also helped solve, unintentionally, the center-of-gravity problem. The placement of the equipment racks increased the overall cabin space. The racks were "line-replaceable units." Equipment could be removed from the racks for repair and replaced within an hour. The racks provided room for future growth should additional equipment be added at a later date. The system also was designed to take advantage of the heat generated by the avionics systems in the racks. Warm air could be vented outside in hot weather, and inside in cool weather.
Other important additions to the helicopter include a voice warning system; a multi-mission, adaptive tactical terminal, which provides crewmembers with real-time, off-board intelligence; system data loading with either 3.5-inch diskettes or flash memory "cards," and improved Night Vision Goggles (NVGs) and NVG compatible displays.
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