Sikorsky has flown its third S-76D prototype for the first time, and is readying the medium twin-engine helicopter for certification testing in the fourth quarter.

This latest model will be used to test and certificate the aircraft's avionics and electrical systems.

To date, the first two S-76D prototypes have chalked up more than 500 flight hours, Sikorsky said, including an indirect lightning test last month.

This certification test simulates lightning strikes to the aircraft, to demonstrate that essential avionics and electrical equipment are protected.

The S-76D is the latest evolution of the S-76 series, offering a 14% increase in take off power and an 8% fuel efficiency over its predecessor, the S-76C++.

The programme was launched in 2005, and introduces two 1,000shp (746kW) Pratt & Whitney Canada PW210S engines, with dual full authority digital engine controls.

Also included is a Thales avionics suite, a "quiet" mode and an optional rotor ice protection system. Sikorsky is also incorporating an all-composite, four-bladed rotor system.

The 15-seat aircraft will be targeted at the increasingly crowded VIP, emergency medical service and offshore transportation markets. Certification and service entry are scheduled for next year.

Source: Flight International