Compare the fixed costs, variable cost, and performance of Sikorsky S-58T to over 500 jets, turboprops, helicopters and piston aircraft, with accurate data from Conklin & de Decker.
In the early 1950’s Sikorsky developed a medium single engine piston helicopter that became both a successful military helicopter (the CH-34) and a very successful commercial helicopter. The S 58, with its large rectangular cabin and flat floor, proved to be a multi purpose machine capable of duty as an airliner, cargo aircraft, external lift machine, EMS ship and fire fighter. It was in production from 1956 until 1968. During this time over 1800 commercial S 58 were produced. At the present writing some 150 are still in commercial service, primarily in fire fighting and external lift roles. In the late 1960’s Sikorsky launched a program to fit the newly developed Pratt & Whitney Canada PT6 “Twin pack” in place of the Wright 989 radial engine. The installation required a new fiberglass nose with two characteristic square nostrils. At the same time the power rating of the main transmission was increased. This combination provides a major increase in the hot and high performance of this helicopter.
The S 58T is a medium twin-engine turbine helicopter. It has a four-bladed, fully articulated rotor with metal blades. The engines used for this helicopter are the Pratt & Whitney Canada PT6T-3 or -6. A four-bladed tail rotor provides directional control. The fuselage is made of conventional aluminum alloys and is mounted on a fixed three-wheeled landing gear. The cabin features two pilot seats up front. Below and behind them is the passenger/cargo cabin. It has a flat floor and one very large sliding door provides ready access to the cabin. When used for passenger transport, it can seat up to 19. When used for external lift, it can carry up to 5000 pounds.
Development of the S 58T was started in early 1970. The first flight of the prototype took place in early 1972. IFR certification was obtained in 1973. From 1971 until 1977 Sikorsky produced modification kits for installation both by itself and by others. A total of about 140 S 58 were converted to S 58T.
Pratt & Whitney Canada PT6T-6 2