Sikorsky S-58T Helicopter
This designation covers a variety of production models, having in common conversion from Wright piston engines to Pratt & Whitney (Canada) PT6T-3 and PT6T-6 Twin-Pac turbines. Aircraft powered by the two different turbine models arc externally indistinguishable. The Sikorsky S-58T helicopter was first flown on 19 August 1970. There were no production aircraft. Rather. Sikorsky offered to sell refit kits or provide the change at its factory. All S-58Ts reflect the features of their original models, and the modifications and upgrades made during their service lives. A number of firms were engaged in S-58T conversions; California Helicopter bought all rights in the early 1980s, and designated military variants as H-34Ts.
At least two of the Nicaraguan H-34As were converted, and one of these served with the Sandinista Air Force. The Fuerza Aerea Argentina operated two ex-American S-58ETs, and later pressed two S-58ETs from Helicopteros Marinos S.A. into service; the latter were used between 18 May and 23 June 1982 during the Falkland Islands conflict. They retained their civil liveries and registrations throughout the conflict. Two of Haiti’s five H-34As were brought to S-58T standards, while two of the three S-58s in Costa Rica were turbine powered. Thailand, after using a large number of H-34s, operated a fleet of S-58Ts as part of its Air Force. These included eighteen ex-CH-34Cs converted by Thai-Am Incorporated. California Helicopter converted twelve UH-34Ds for the Indonesian Air Force during the 1970s.