Sikorsky S-76

S-76
	Galician Coast Guard S-76C+
Role	SAR/utility helicopter
Manufacturer	Sikorsky Aircraft Corporation
First flight	March 13, 1977
Primary user	CHC Helicopter Corporation
Number built	774 as of March 2011[citation needed]
Variants	Sikorsky S-75

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The Sikorsky S-76 is an American medium-size commercial utility helicopter. The S-76 is powered by two turboshaft engines, which drive both the main and tail rotors, each with four blades. The S-76 landing gear is retractable.

[edit] Design and development

An early production Sikorsky S-76A owned by Canadian Helicopters and used as an air ambulance.

The development of the S-76 began in the mid-1970s, with the design goal of providing a medium helicopter for corporate transportation and the oil drilling industry. Sikorsky's development of the UH-60 Black Hawk served as the basis for the S-74, which was later re-designated the S-76 Spirit in honor of the U.S. Bicentennial. The design accommodates 2 pilots and 12 passengers and was initially powered by two Allison 250 C30 turboshaft engines of 478 kW (641 hp) each. The prototype first flew on March 13, 1977.^[2] The name "Spirit" was officially dropped by the company on October 9, 1980.^[3]^{[verification needed]}

The first production variant was the S-76A. In 1982 this model set class records for range, climb, speed and ceiling. Several airlines operate the S-76A on scheduled services including Helijet Airways of Vancouver, British Columbia, Canada.

The S-76 Mk II was introduced in 1982 and the S-76B in 1987, with its top speed of 155 kn (287 km/h) at sea level. Over 500 S-76s had been delivered by early 2001.^[2]

The S-76C+ was produced until December 2005. It is equipped with twin Turboméca Arriel 2S1 engines with FADEC and a Honeywell EFIS suite from .^[2] The aircraft incorporates active noise suppression, vibration dampers and a composite main rotor.

On January 3, 2006, the S-76 C++ replaced earlier models in production. It is powered by two Turbomeca Arriel 2S2 engines and incorporates an improved and quieter transmission as well as minor changes in the interior equipment and avionics. There were 92 orders for this model as of January 2006.

Development of the follow-on S-76D model has been subject to delays due to technical problems in expanding the flight envelope.^[4] It will be powered by 1,050 hp (783 kW) Pratt & Whitney Canada PW210S engines driving composite rotors and will incorporate active vibration control. A prototype made its first flight on 7 February 2009 and type certification is expected in 2011, with deliveries anticipated by the end of the year. Three prototypes will be used in the certification program. One aircraft will be used to obtain certification of an optional electric rotor ice-protection system. Performance is anticipated to be substantially improved with the added power, but initial certification will retain the same 11,700 lb (5,307 kg) gross weight and maximum 155 kn (287 km/h) cruise speed.^[5]

[edit] Variants

[edit] Civil

S-76C search and rescue helicopter operated by Norrlandsflyg.

S-76C owned by LG Electronics as a VIP transport

RAAF S-76++

S-76A : Original production version, powered by two 485 kW (650 shp) Rolls-Royce (Allison) 250-C30 turboshaft engines. Large number modified to S-76A+, A++, C, and C+. 284 manufactured.
S-76A Utility : Utility transport version, equipped with sliding doors and a strengthened floor.
S-76A+ : Unsold S-76s were fitted with two Turbomeca Arriel 1S turboshaft engines. 17 manufactured.
S-76A++ : S-76 helicopters fitted with two Turbomeca Arriel 1S1 turboshaft engines.
S-76A Mk II : Improved all-weather transport version, fitted with more powerful engines, and other detail improvements.
S-76B : Powered by two Pratt & Whitney Canada PT6B-36A or Pratt & Whitney Canada PT6B-36B turboshaft engines. 101 built.
S-76C : Powered by two 539-kW (981-shp) Turboméca Arriel 1S1 turboshaft engines. 43 manufactured.
S-76C+ : Uprated version, fitted with improved Turboméca Arriel 2S1 turboshafts with FADEC. 35 manufactured.
S-76C++ : Turboméca Arriel 2S2
S-76D : Powered by two Pratt & Whitney Canada PW210S.

[edit] Military

AUH-76 : Armed utility transport version, developed from the S-76 Mk. II.
H-76B : Military version of the S-76B.
H-76N : Planned naval version of 1984, not implemented.

[edit] Experimental derivatives

Sikorsky S-76 SHADOW

A S-76B prototype helicopter modified as a fantail demonstrator for the RAH-66 program at 1991 Paris Air Show

Sikorsky S-75: The Advanced Composite Airframe Program (ACAP) was an all-composite Sikorsky early LHX proof of concept aircraft. It mated a new composite airframe with S-76 engines, rotors and powertrain components.^[6]

Sikorsky S-76 SHADOW: Boeing-Sikorsky MANPRINT study. The original concept of the LHX program was to produce a one-man helicopter that could do more than a two-man aircraft. The Sikorsky (S-76) Helicopter Advance Demonstrator of Operators Workload (SHADOW) had a single-pilot advanced cockpit grafted to its nose. The purpose was to study the MANPRINT or human engineering interface between the pilot and the cockpit controls and displays. The cockpit was the prototype of a single-pilot cockpit designed for use on the prototype RAH-66 Comanche armed reconnaissance helicopter. The cockpit was designed so sensors would feed data to the pilot through helmet mounted displays. The MANPRINT study determined that single-pilot operation of the Comanche was unsafe, and would result in pilot overload. As result of this study, the Comanche was designed to be operated by a crew of two.^[7]

[edit] Operators

[edit] Civil

The S-76 is in civil service around the world with airlines, corporations, hospital, government operators and, notably, the British Royal Family. The world's largest civilian fleet is the 79 Sikorsky S-76 helicopters operated by CHC Helicopter Corporation.^[1]