Sikorsky S-76 Spirit

Summary

Description

The development of the Sikorsky S-76 began in the mid-1970s. Initially designated the S-74, it was later renamed the S-76 in honor of the U.S. Bicentennial. Sikorsky's objective was to produce a medium helicopter suitable for both corporate transportation and the offshore oil drilling industry. Utilizing design technology from the S-70 helicopter, the S-76 was Sikorsky's first helicopter designed exclusively for the commercial market, intended to meet stringent FAR and military standards for robustness. The program was announced on 19 January 1975, with early contract acceptance facilitating market research during development. Prototype construction commenced in May 1976, leading to the maiden flight on 13 March 1977. Initial FAA type certification was granted on 21 November 1978, and the first customer delivery occurred on 27 February 1979. The helicopter was briefly named "Spirit" in late 1978, but this name was officially discontinued by Sikorsky on 9 October 1980 due to potential translation complexities.

The S-76 features a conventional helicopter design. It is equipped with a four-bladed fully articulated main rotor and a four-bladed anti-torque rotor mounted on the port side of the tailboom. Power is supplied by two turboshaft engines positioned above the passenger cabin. Prototypes and initial production models were powered by Allison 250-C30 engines, rated at 650 shp (480 kW) for takeoff. These engines are connected to the main rotor system through a three-stage main gearbox. The main rotor utilizes a single-piece aluminum hub with elastomeric bearings designed to reduce maintenance requirements. The rotor blades incorporate titanium spars, a ten-degree twist to optimize loading distribution during hovering, a non-symmetrical airfoil section featuring a drooped leading edge, and tapered, swept-back tips. Ice protection measures have been integrated into the rotor blades on later S-76 models. Flight controls are servo-assisted and include a Stability Augmentation System. A retractable nosewheel undercarriage is employed to minimize drag, contributing to improved cruise speed, particularly in the S-76A variant. Emergency flotation gear, utilizing helium-filled bags for buoyancy, can be fitted for operations over water. The fuselage construction incorporates a combination of metal and composite materials, with a fiberglass nose, a cabin area structured with a light alloy honeycomb, and a tailboom built as a semi-monocoque light alloy assembly. The cockpit configuration typically accommodates two pilots in a side-by-side arrangement forward of the cabin. The cabin can be configured to seat up to 12 passengers in a high-density arrangement or between four and eight passengers in a luxury configuration. Later S-76 models can be operated by a single pilot when equipped with a specially configured cockpit.

The Sikorsky S-76 platform is not primarily designed or configured for offensive military operations, and consequently, standard commercial variants lack a conventional armament suite typical of combat helicopters. However, the AUH-76 "Dragon Lady," a specialized armed utility transport variant based on the S-76 Mk. II delivered to the Philippine Air Force in 1983, was initially equipped with two fixed forward-firing M134 7.62 mm miniguns positioned one on each side, and a 7-round rocket pod also mounted on each side, in addition to radar altimeters. The M134 miniguns were subsequently replaced with M2P Machine Guns when they became unserviceable. Standard S-76 models are typically employed in roles such as passenger transport, VIP transportation, search and rescue, and emergency medical services, and do not feature internal or external hardpoints for carrying weaponry.

The maximum gross weight for the S-76C++ variant is documented as 11,700 lb (5,306 kg).

Early in its operational history, the S-76 achieved significant popularity for offshore operations, primarily supporting the transportation of personnel and equipment to and from oil and gas platforms. Numerous operators globally procured the type for this specific mission profile. In 1982, the S-76A variant established class records for range, climb speed, cruise speed, and service ceiling. Beyond its utility in the energy sector, the S-76 has been adapted for diverse roles, including scheduled airline services with operators such as Helijet Airways in Canada. The type has also been utilized in governmental transport, including for political leaders during events such as the 2005 United Kingdom general election. The S-76 platform has been a favored asset among VIP customers, with at least ten countries operating it for head-of-state transport by 2020. The platform also served in experimental programs, notably the S-76 SHADOW, which supported the RAH-66 Comanche development, and in autonomous flight demonstrations conducted during the 2010s. Towards the conclusion of its production phase, some operators initiated the replacement of their S-76 fleets with more recent medium-lift rotorcraft such as the AgustaWestland AW139. By early 2020, sales of the S-76D were restricted in the United States but remained available for purchase in other international markets. Documented state and military users include the Argentine Air Force, the Japan Coast Guard, the Royal Jordanian Air Force, the Philippine Air Force, the Spanish Air and Space Force, and the Royal Thai Navy.

Main Variants:

• S-76A: The original production version, powered by two Rolls-Royce (Allison) 250-C30 turboshaft engines, served as the base for several later modifications.

• S-76A Utility: This utility transport variant of the S-76A featured sliding doors and a strengthened floor to enhance its cargo-carrying capabilities.

• S-76B: Equipped with Pratt & Whitney Canada PT6B-36A or PT6B-36B turboshaft engines, this variant offered improved performance compared to the earlier models.

• S-76C++: Powered by Turbomeca Arriel 2S2 engines, this version featured an improved and quieter transmission, along with minor enhancements to the interior equipment and avionics.

• S-76D: The S-76D is powered by two Pratt & Whitney Canada PW210S engines, incorporating a Thales Topdeck avionics suite and an improved noise signature.

Technical specifications

Current operating countries

Country		Units
	Philippines	9
	Spain	8
	Thailand	4

Numbers in parentheses, e.g. '(+5)', indicate units ordered but not yet delivered.

All operators

Spain • Guatemala • Hong Kong • Honduras • Iceland • Jordan • Philippines • Thailand