Sikorsky S-76 Helicopter, USA

A multi-role, medium-size utility helicopter, the Sikorsky S-76 was manufactured by Sikorsky Aircraft Corporation, US. It was principally designed and developed for CHC Helicopter Corporation, Canada. The maiden flight of S-76 took place on 13 March 1977. Approximately 700 S-76 helicopters have been developed for 192 operators in 44 countries.

Operations carried out by the S-76 include executive passenger transport (VIP), emergency medical services (EMS), search and rescue operations (SAR) and offshore passenger and material transportation. The S-76 can accommodate 14 people including two pilots. It has retractable landing gear.

Sikorsky Aircraft Corporation received Federal Aviation Administration (FAA) certification for its S-76C++, a variant of the S-76, in January 2006.

Variants

The S-76 is available in ten variants: S-76A, S-76A Utility, S-76A+, S-76A++, S-76A Mk II, S-76B, S-76C, S-76C+, S-76C++ and S-76D.

The S-76A is the first model in the S-76 series. About 284 S-76A helicopters have been manufactured. The second variant, the S-76A Utility, is an advanced version of the S-76A. The S-76A Utility is fitted with sliding doors and a strengthened floor.

The S-76A+ variant has two Turbomeca Arriel 1S turbo shaft engines. An all-weather transport model, the S-76A Mk II variant was derived from the S-76A+ by equipping the latter helicopter with powerful engines.

S-76Bs were equipped with two Pratt and Whitney PT6B-36A or PT6B-36B turbo shaft engines. An upgrade of the power capacity of the engines to 539kW led to the development of the S-76C.

Another variant, S-76C+, was developed by upgrading the S-76B engine with full-authority digital engine controls (FADEC). The S-76C+ is powered by enhanced Arriel 2S1 turboshafts.

Another new variant, S-76C++, was developed by overhauling the engines, avionics and new gearboxes of the S-76C. The presence of powerful engines in the S-76C++ increased the take-off weight by 450lbs. The S-76C++ also includes a new cabin for VIP transport.

Orders and deliveries

Offshore Logistics Inc (OLOG) procured 35 S-76 helicopters and also purchased rights for an additional 24 S-76s on 14 June 2005.

Two S-76 helicopters were acquired by China Eastern General Aviation Corporation (EGAC) on 1 August 2005 to affirm oil offshore operations in the Bohai Bay area of northern china.

On 27 October 2005 JC Bamford Excavators Ltd bought an S-76C++ helicopter. US Helicopter Corporation procured an order for four S-76C++ helicopters from Sikorsky on 27 February 2006. Sikorsky also received an order for three new-build S-76C++ helicopters from Malaysian Helicopter Service (MHS) on 29 June 2006.

Two S-76C++ helicopters were acquired by Macau-based Wynn Resorts on 17 October 2006. It will be used for VIP transport in the Hong Kong and Macau regions. Aero Med Spectrum Health of Grand Rapids, Michigan bought an S-76C++ helicopter from Sikorsky Aircraft Corporation on 17 October 2006.

Sikorsky Aircraft Corporation signed a contract with Boston MedFlight to supply an S-76C++ helicopter for air medical transports. EraMed, LLC operates S-76C++ in place AS-365N2 Dauphin.

In November 2007 the Royal Household, UK awarded a contract to Sikorsky Aircraft Corporation to provide an S-76C++. The S-76C++ entered into service in September 2009. It was delivered to the Royal Travel Office on November 2009.

The deliveries of all helicopter variants have been completed.

Development

Sikorsky Aircraft Corporation commissioned the development of a medium business helicopter, UH-60 Black Hawk, in the 1970s. The company focused on airlines that were using medium business helicopters and the oil drilling industry. Sikorsky built the S-74, which was renamed the S-76 Spirit. The S-76 Spirit was equipped with two Allison 250 C30 turbo shafts with the capacity to generate 478kW of power each.

In 1982 the S-76A, also known as the S-76 Mk II, was developed. The S-76A provides high-range climbing. It is being operated by Helijet Airways of Vancouver, British Columbia, Canada.

In 1987 an advanced version, S-76B, was introduced. It can fly at speeds of 155k at sea level. About 500 S-76s were delivered by early 2001. Turbomeca Arriel 2S1 engines were deployed in the S-76C+ until December 2005. The main rotor of the S-76C+ was manufactured using composite material. Increased active noise and vibration dampers were used to provide more comfort for passengers. Production of the S-76C+ was completed in December 2005.

The S-76C++, which features an intake air filter and an improved and quieter transmission, was launched later. It is equipped with upgraded interior equipment and electronics. The production of S-76C++ was completed in January 2006. The helicopter is powered by a Turboméca Arriel 2S2 turbo shaft engine.

The S-76D is currently under development. It will be equipped with a Pratt and Whitney 210S engine that can produce about 1,050shp of power. Vibration control and composite main rotors will be installed.

The maiden flight of S-76D was completed in February 2009 and type certification is expected in 2010. The first delivery of S-76D is expected in late 2010. The revolutions per minute (rpm) of the rotor will be self adjusted. The higher rpm is applied during take-off and lower rpm setting is applied for enhancing cruise range.

Cabin

The S-76C++ helicopter has a large rectangular cabin. The length and width of the cabin are 2.41m and 1.93m respectively. The height and area of the cabin are 1.35m and 4.65m² respectively. The baggage volume and cabin volume are 1.08m³ and 5.78m³ respectively.

The helicopter also has a spacious cabin interior, an active vibration control system (AVCS), reduced interior noise, two cabin doors with pop-out windows and two cockpit doors.

Cockpit

The cockpit is equipped with a Honeywell primus weather radar, dual comm / nav radios, an automatic direction finder, dual attitude and heading reference systems (AHRS) and air data computers, a radio altimeter, a mode C transponder, dual VORs with glideslope, distance measuring equipment (DME) and a cockpit voice recorder (CVR).

Avionics

The avionics suite installed in the cockpit of the S-76C++ includes a Honeywell four-tube electronic flight instrument system (EFIS), a four-axis fully coupled autopilot, an integrated instrument display system (IIDS) and a Honeywell enhanced ground proximity warning system (EGPWS).

The S-76D's cockpit will be fitted with an avionics suite that will include a Thales Top Deck avionics system, four-axis fully coupled autopilot, an EGPWS, a traffic collision avoidance system (TCAS1), a Honeywell Primus 660 weather radar, a health usage monitoring system (HUMS), a Thales digital map and a Collins Pro Line 21 comm / nav radio suite.

Engine

The S-76 is powered by two Turbomeca Arriel 2S2 turbo shaft engines. Each engine can produce a take-off power of 688kW. The length and height of the engine are 1.156m and 0.6m respectively. The engine can generate maximum continuous power of 621kW.

The engine has simple design that consists of five modules. This provides simpler maintenance and reduces operating cost through optimised acceleration modes. The Arriel 2S2 turbo shaft engine produces 6% more power than the Arriel 2S1 turbo shaft engine. It is also equipped with a double-channel electronic engine control unit (EECU), which measures fuel, ignition timing and other parameters. The endurance of the Arriel 2S2 is 3,000h.

The Arriel 2S2 is suitable for helicopter carrying missions such as EMS, SAR, police, VIP, aerial work, corporate and off-shore liaison.

Performance

The S-76 can fly at a maximum speed of 287km/h. The ferry range and service ceiling of the helicopter are 639km and 4.572m respectively. The maximum take-off weight of the S-76 is 5,306kg while the empty weight is 3,177kg.