The DFC90 adds the precision of an attitude-based flight control system and Avidyne’s innovative, safety-enhancing Envelope Protection capability.
The DFC90 has all the standard vertical and lateral modes of operation of a turbine-class autopilot system, including Flight Director (FD), Altitude Hold (ALT), Airspeed Hold (IAS), Vertical Speed Hold (VS), Heading (HDG), and Navigation (NAV, APPR, LOC/GS, GPSS). Customers upgrading from the STEC 55X will notice several major performance and feature improvements (see list under the Features tab).
There are many other improvements, such as a dedicated Vertical Speed knob, pitch hold mode, wide autopilot engagement, additional annunciations in PFD 8.0, a dedicated GPSS button, automatic Back Course Approach selection, multiple color annunciations to indicate armed and active states, intercept mode annunciations, and Avidyne’s hallmark ease of use.
For envelope protection, available lift and speed margin are calculated constantly in the background whenever any mode, including Flight Director modes, are in operation. As the aircraft approaches stall, the autopilot acts unobtrusively to gradually reduce maximum bank and Vertical Speed just enough to keep the wing flying, while annunciating the condition to the pilot. As a result, departure from controlled flight is prevented with the least obtrusive impact on achieving mission level objectives like navigation, climb or approach. Overspeed is handled similarly, with anticipation and minimal but effective inputs. In Flight Director modes, all these actions appear as guidance cues with corrections blended into the "V-bar" commands.