HAI Convention News

Sikorsky moves to update S-76

 - February 20, 2007, 10:58 AM

While celebrating the delivery of the 615th S-76, Sikorsky representatives revealed yesterday the details surrounding two new models, the S-76C++ and S-76D, that will modernize the line for years to come.

The first of the new models, the S-76C++, is currently available for order, after the S-76C+ line recently sold out. Sikorsky anticipates deliveries late this year of the new model, which incorporates an upgraded engine, new VIP interior, health and usage monitoring system (HUMS) and new gearbox. Pricing on the S-76C++ remains the same as the S-76C+, according to Sikorsky.

“Customers want more for the same price,” said Jeff Pino, Sikorsky senior vice president of sales and commercial programs. “This announcement represents Sikorsky’s commitment to our customers to improve the S-76 to give more power, speed, payload, range, lifting power and lower maintenance costs.”

Many of the improved characteristics of the S-76C++ will result from the new engine, a derivative of Turbomeca’s 2S series dubbed the 2S2. The 2S2 will provide a 5- to 6-percent increase in horsepower equating to 350- to 450-pound increase in Category A takeoff weight at high temperatures. In cooperation with Turbomeca, Sikorsky has also developed a new inlet barrier filtration (IBF) system that will reduce engine degradation without the power loss normally associated with barrier filters due to re-engineering of the intake flow.

Additional improvements, including a new cabin soundproofing system using Keystone Helicopters’ Silencer technology and Sikorsky’s Quiet Zone gearbox, will reduce the noise level in the S-76C++ cabin to approximately that of an airline cabin, according to Pino. The Quiet Zone gearbox uses a proprietary technology to “superfinish” transmission gears, changing the shape of the gears and providing a mirror-like finish that lowers noise in the cabin by 4 dB while increasing gear life and reliability.

The S-76C++ will also feature a Honeywell VXP HUMS to provide rotor track and balance, drive system monitoring and an option for high-speed shaft monitoring.
Scheduled for delivery in mid-2008, the S-76D will incorporate many of the features of the S-76C++ and improve upon others. For example, a new Pratt & Whitney PW210S engine, specifically designed around the new S-76D platform, will replace the Turbomeca 2S2 and provide an additional 1,000 pounds of lifting capacity at takeoff in hot conditions.

“We knew that we wanted a new engine, and Pratt & Whitney brought us a deal to put a new centerline engine on our aircraft,” Pino said. “They would size it, scope it and figure it for our aircraft. That deal was impossible to turn down.”

The S-76D is expected to increase high-and-hot lifting capability by 1,400 pounds, thanks to the new engine, and a new all-composite main rotor blade design that will provide an additional 400 pounds. It also will incorporate the same rotorcraft icing protection system (RIPS) currently being certified on the S-92.

“The chord, airfoil and tip shape are all going to be redone,” Pino said. “We’re going draw a lot of experience from the Comanche, and the capabilities of that airfoil were pretty spectacular.”

The tail rotor is also being redesigned to reduce noise. “We should lose two decibels in takeoff, and 1.5 decibels in flyover,” said Pino. “While this doesn’t sound like a lot, it will allow the S-76D to meet the so-called Grand Canyon noise standards.” According to Pino, the S-76D would be the only helicopter in its class to meet Special FAR 52: Special Flight Rules in the Vicinity of Grand Canyon National Park.

Sikorsky is currently holding a competition for the S-76D avionics supplier to provide a state-of-the-art glass cockpit; entrants include L3, Thales, Honeywell, Rockwell Collins and others. The avionics package is expected to be announced within the next few months. In addition to the new cockpit and other upgrades, the S-76 will also feature a new streamlined exterior.