February 25, 2013
Credit: Sikorsky Aircraft
Sikorsky's S-76 has proved popular in the medium commercial helicopter market, with more than 800 produced since deliveries began in 1979. Now the company has switched production to the S-76D, its eighth rendition of the proven design.
The aircraft received FAA certification in October 2012, and is on track to be accorded Transport Canada certification in April, followed by European and Japanese approval in May. First deliveries are expected by mid-2013.
The D model is targeted at the same basic markets as its predecessor—offshore, executive transport, emergency medical service and search-and-rescue. But the aircraft offers some significant improvements over earlier S-76s, based on discussions with owners, pilots and maintainers, says Dan Hunter, director of programs for Sikorsky Global Helicopters, the manufacturer's commercial division.
“They had a lot of input, and we made a lot of changes based on that,” he says, noting that many product improvements came from the larger S-92. “As they developed them, we stole them.”
Among those improvements, the principal changes involve more powerful engines, new rotor blades and an integrated glass cockpit designed to simplify single-pilot operations.
The twin Pratt & Whitney Canada PW210S turboshafts, which have dual-channel digital controls, produce 14% more takeoff power and burn 8% less fuel than the Turbomeca Arriel 2S2 engines that power the S-76C++.
The only changes to the main rotor system are to the blades, using the Advanced Growth Blade developed for the S-92 and adapted to the S-76D. These all-composite blades have a wider chord for more lift and reshaped blade tips for less noise. Sweep and taper are used to reduce blade-tip vortex strength and minimize compressibility. The tips are swept back approximately 30 deg.