Alliant is a cooperative effort between Avidyne and S-Tec to transform the cockpit - and enhance the autopilot performance - of Beech King Airs. The Alliant system replaces all flight instruments, gyros and air data computers with an integrated package of dual primary flight displays (PFD), a FlightMax multifunction display (MFD) and a new digital electronic autopilot.
The Alliant system was first certified on the Super King Air 200 family last fall, but approvals are expected soon for other members of the King Air line, the most popular turboprop family of all time. And priced at about $170,000, the Alliant conversion makes economic sense for King Airs of most any age. The Alliant system very closely resembles the avionics package Avidyne and S-Tec developed for the single-engine Piper Meridian turboprop. The core of the system is the dual EXP5000 10.4-inch diagonal PFD displays that show everything necessary to fly the airplane, and much more than was available on the host of mechanical instruments they replace. Housed within the PFDs are electronic attitude and heading reference systems (AHRS) and digital air data computers. Without need of any moving parts, the AHRS and air data computers perform all of the functions of at least six separate spinning gyros and six mechanical-pneumatic instruments that they replace.
In the Alliant system all information critical to safe IFR flight is completely dual, and is constantly compared to detect errors. For example, if one of the air data computers were to fail or develop a leak in the static system, a warning message would appear on the PFD. Armed with that information the pilot could then compare the two PFDs with the standby instruments and easily determine what had failed and continue the flight using only the valid information. Because the Alliant system is all digital electronic there is no need for the alternating current bus or inverters that are essential to operate the mechanical flight instruments they replace. A total loss of AC power in a conventional King Air avionics system is a true life-threatening emergency, but won't be a big deal in the Alliant system. After the conversion the only instruments that depend on AC electrical power are the engine torque gauges, and pilots can easily set power by reference to the other engine instruments if those were to fail.
Multifunction display chores are handled by Avidyne's EX500 system, which can show XM satellite weather, Jeppesen charts, the airplane's weather radar, terrain and traffic warnings and text messages via Avidyne's MultiLink system. The EX500 is the size of a traditional weather radar, so it is not as large as the multifunction displays in some glass cockpits, but the system's capability is enormous.
The third major element of the conversion is S-Tec's 2100 autopilot that is fully integrated into the system. The 2100 has the modes you expect to find in an autopilot designed for turbine airplanes, and uses the precise attitude and yaw rate from the Avidyne AHRS to control the airplane.
I had a chance to fly the first King Air 200 converted to the Alliant system and the transformation is impressive. The 25-year-old airplane had new paint and interior, so it looked great, and then when I looked in the cockpit, it looked new, too. The dual stacks of engine gauges and the toggle switches to control lights and systems were still there, but the big glass displays dominated the cockpit and lent an up-to-date feel compared to the old "steam gauges" they replace.
New radios are not part of the Alliant package, but most owners will use the opportunity to update the com and nav. This airplane had new dual Garmin GNS 430 com/nav/GPS systems, Garmin Mode-S transponders and a new audio panel, so the transformation was complete.