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Sikorsky S-76

1977 COLD WAR MODERN AIRCRAFT

History

The S-76 model was developed by Sikorsky Aircraft for the highly competitive mid-size commercial helicopter market. Its design was influenced by the company's work developing the S-70, which became the famous military UH-60 "Black Hawk". This product started with the "S-74" in the mid-1970s and was intended for use in the oil industry and the VIP/corporate transport sector. In keeping with the American celebrations of 1976, the bicentennial of the founding of the United States, the model was renamed the "S-76".

The final product became a popular entry point for the mid-range elevator category, with nearly 1,100 units produced.

The S-76 has a twin-turboshaft engine layout, and these systems are mounted above the passenger cabin in the usual way. The cockpit sits two crew members side by side behind a short nose assembly, and visibility outside the cockpit is generally good.

Access is via automotive-style hinged doors, while the passenger area has rectangular sliding doors on either side of the fuselage. The tailstock is contoured to complement the existing lines of the fuselage and houses a drive shaft that drives a four-blade tail rotor offset to port.

This is used to counteract the torque effects caused by the four-blade main rotor system mounted on top of the cabin. Wheeled tricycle landing gear is installed to allow ground walking and fully retractable to maintain aerodynamic efficiency during flight.

The original production was the S-76A, which was powered by 2 Rolls-Royce (Allison) 250-C30 turboshaft engines, each producing 650 hp. Around 284 units were subsequently put into production. The utility-oriented profile became the S-76A "Utility," a brand that had a reinforced cabin floor.

The S-76A+ is an S-76 with the French Turbomeca Arriel 1S turboshaft engine, 17 of which were modified in this way. Likewise, the S-76A++ is powered by 2 x Turbomeca Arriel 1S1 turboshaft engines. The S-76A Mk II is an improved all-weather tugboat with improved and upgraded turboshaft engines.

The S-76B was produced with 2 Pratt & Whitney Canada PT6B-36A or PT6B-36B engines, 101 were produced to this standard. The S-76C received 2 Turbomeca Arriel 1S1 engines, with 43 subsequently produced. The S-76C+ is similar, but with 2 Turbomeca Arriel 2S1 engines (full digital FADEC support), followed by 35.

The S-76C++ followed, which featured the Turbomeca Arriel 2S2 engine. The S-76D is equipped with 2 x Pratt & Whitney Canada PW210S engines and Thales "Topdeck" avionics.

The S-76C++ variant is piloted by two people and can accommodate 13 people. It has an overall length of 52.5 feet and a height of 14.5 feet. Curb weight is listed as 7,000 pounds, for a total of 11,700 pounds.

The 2 Turbomeca Arriel units have an output of 922 horsepower, a top speed of 180 mph, a range of 475 miles, and a service ceiling of approximately 13,800 feet.

Military variants of the S-76 model are the "AUH-76" (based on the aforementioned S-76 Mk II model) and the H-76 "Eagle" proposed for maritime use - although she was not used by either party. The S-76 Shadow was used to develop the U.S.

Army's (eventually abandoned) RAH-66 Comanche light attack stealth helicopter program (described in detail elsewhere on this page). An S-76B was also modified with a fantail rotor unit (pipe) for the same procedure and was shown at the 1991 Paris Air Show.

Operators of the S-76 eventually went from Argentina and China to Turkmenistan and the United Kingdom, including military and civilian roles (and some coast guard service). Many of these original operators continue to operate Sikorsky Helicopters. Canadian CHC Helicopters operates nearly 80 S-??76 platforms serving the offshore oil and gas industry.

Bristow Helicopters in Scotland is another well-known operator of this type.