The Sikorsky HH-52 Seaguard (company designation S-62) was an early amphibious helicopter designed and produced by the American helicopter manufacturer Sikorsky Aircraft. It was the first of the company's amphibious rotorcraft to fly. The S-62 was originally developed as a commercial venture during the late 1950s. It combined the dynamic elements of the Sikorsky S-55 with a boat hull-shaped fuselage and a single lightweight turboshaft engine. The prototype S-62 conducted its maiden flight on 22 May 1958, powered by a single General Electric T58-GE-6 turboshaft engine. It underwent evaluation at the Naval Air Test Center in Patuxent River, Maryland, at Sikorsky's own expense as part of its effort to promote the S-62 to the United States Coast Guard (USCG). The USCG would procure 99 S-62s, which it initially designated as the HU2S-1G Seaguard, and later re-designated as the HH-52A Seaguard. It was primarily operated by the USCG for air-sea rescue missions. Various other operators opted to procure the S-62 for their own purposes, from airliners to utility transporters, and foreign air services. It was widely used into the 1980s, by which point many operators elected to replace the type with newer rotorcraft. The HH-52 was withdrawn from USCG service during 1989 in favour of non-amphibious rotorcraft, such as the Eurocopter HH-65 Dolphin, which rely solely on the use of a winch from a low hover to conduct rescue operations. Development Development of the S-62 was launched by Sikorsky during the late 1950s, the initiative was initially pursued as an independent commercial venture. In concept, the project combined the dynamic elements of the earlier Sikorsky S-55 with a boat hull-shaped fuselage and a single lightweight turboshaft engine. This was a relatively ambitious design for the era, being the first of Sikorsky's amphibious helicopters. On 22 May 1958, the prototype S-62 performed its maiden flight; in doing so, it had beat its larger Sikorsky S-61 sibling into flight by almost a year. This prototype was powered by a single General Electric T58-GE-6 turboshaft that had been derated from 1,050 hp to 670 hp, powering an identical main and tail rotor to that of the S-55. At Sikorsky's own expense, it funded a "fly before you buy" test programme at the Naval Air Test Center in Patuxent River, Maryland; the company actively promoted the type to the United States Coast Guard (USCG) in particular. The results of this test programme was largely positive,