“We did not meet that [two-push criteria] everywhere,” Hunter said. “There are some places that require more than two button presses because there is no way around it. But if they didn't design the software with that in mind, they had to come to me and ask permission to do it another way.”
The Thales system is fully coupled to the helicopter's flight control system so that by punching the appropriate button, most flight commands are automatically recognized and initiated at the appropriate time, such as flying to an ILS localizer and coupling with the ILS to fly the approach to touchdown.
The overall system is designed to provide everything the pilot needs in a single-pilot operation, requiring the absolute minimum amount of effort. It basically does everything but brew coffee, something to consider for a future E model, perhaps. (See “Avionics Suite as Computer” sidebar.)
Also new to the S-76D is a Goodrich Vigor HUMS as baseline equipage. The system provides the operator with a detailed analysis of the health of the aircraft, feeding the information to the operator and, at the request of the user, allowing that information to be fed to Sikorsky's Fleet Management Operations Center (FMOC) where it is monitored on a 24/7 basis and analyzed for trends in the aircraft's maintenance and usage. The FMOC personnel look for and evaluate any inconsistencies in performance against fleet trends to alert operators to potential maintenance problems.
The use of HUMS also allows the FMOC to recommend changes in maintenance programs. Hunter noted that the S-76D HUMS comes from the S-92 program, and those being used on that aircraft allowed operators to go from 4,700-hr. TBO to 9,400 hr. on the swash plate alone.
Hunter said that at this time the HUMS data are accessed through a USB port in the baggage compartment. However, several formats that operators can use are in the planning stage, including a card in the cockpit to allow the pilots to access the information, as well as eventual options for remote wireless access.
The D model is also equipped with a Moog active vibration suppression system, using force generators that measure the vibration frequencies and produce exact opposite frequencies to counter them. Operators can order up to six of these force generators, although each one adds weight and cost. While each operator will determine how much vibration is acceptable to the mission, Hunter said Sikorsky expects three to four to be the average.
The anti-vibration system is one of only three systems using AC power, although Sikorsky is looking at a program that may change the anti-vibration system to DC.
Sikorsky went with a totally redesigned electrical system for the S-76D “to address some customer issues and to maximize compliance with the FAA regulations,” Hunter said. He noted that the systems in the legacy aircraft were not satisfying D model requirements, such as providing additional torque to start the PW210S engine, requiring an increase from the legacy 200-amp rated generator to a 300-amp unit. The redesign put all the systems except anti-vibration, windshield heat and RIPS on a 28-volt DC electrical system newly developed by Sikorsky just for the S-76D.