<p>USAF interest in the Sikorsky S-61 Sea King began in 1962 when three US Navy HSS-2s were borrowed to resupply the 'Texas Tower' radar outposts in the Atlantic. Designated CH-3A, the three aircraft (62-12571/62-12573) were stripped of their naval anti-submarine equipment and had seats for up to 25 installed, plus cargo provision. So successful were they that an additional three were procured as CH-3Bs (62-12574/62-12576) and used on similar tasks. Operational experience with these aircraft led to the USAF adopting the type on a wider basis with the CH-3C variant, which was tailored to USAF requirements. This aircraft dispensed with many naval features, although it retained the boat hull. The fuselage sponsons were redesigned further back along the fuselage to house a new main landing gear, and the aircraft was given a nosewheel. More importantly, the rear fuselage was reshaped to incorporate a rear loading ramp.
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<p>The first flight of a CH-3C was on 17 June 1963, and a total of 75 was built (62-12577/62-12582, 63-9676/63-9691, 64-14221/64-14237, 65-5690/65-5700, 65-12511, 65-12777/65-12800). The type was employed on a number of long-range transport tasks, including the support of air liaison officers working in the field with army units. In February 1966 the CH-3E was introduced, this differing by having uprated 1,500-shp General Electric T58-GE-5 engines in place of the 1,300-shp T58-GE-1. Forty-five of this model (66-13291/66-13296, 67-14702/67-14725, 69-5798/69-5812) were built, and a further 41 CH-3Cs re-engined to the same standard.
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<p>Perhaps the best-remembered of the USAF H-3s were the HH-3Es, of which eight were built as new (66-13284/13290, 68-8282) and 50 modified from CH-3E. The HH-3E was an answer to a USAF requirement for a long-range combat rescue helicopter, and was fitted with titanium armor, internal fuel tanks of 30 per cent greater capacity, additional 200-US gal tanks fitted to the sponsons and defensive armament. After initial service, a semi-retractable refueling probe was added. The HH-3Es were heavily committed in Southeast Asia from June 1967, where they were promptly nicknamed the 'Jolly Green Giant'. Countless saves of downed airmen were accomplished. Thirty-one aircraft were lost during the war. In addition to regular rescue missions, HH-3Es were also used in support of the Apollo manned spaceflight program.
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<p>Following the end of the Vietnam War, the CH/HH-3E remained in widespread USAF service, many being passed to the ANG and AFRes. The final aircraft were withdrawn (from the active-duty 41st Rescue Squadron at Patrick AFB, FL) in 1994, having been replaced by the HH-60G.
