Come up with a great idea and the rotary world will apparently whoop-whoop a path to your door. That, in fact, is just what has happened with Genesys’ HeliSAS Autopilot and Stability Augmentation System, which has quietly become one of the most successful helo aftermarket launches in memory. HeliSAS (short for helicopter stability augmentation system) is the first of its kind certified for Part 27 rotorcraft, and if sales are any indication, there was a definite need for the technology.
As is standard for autopilots, the primary function of the HeliSAS is to free up as much of a pilot’s time and attention as possible. The HeliSAS stands out because it’s aiming at light to midsized Part 27 helicopters. Most of these are single-pilot, fall into the light to midsized range and aren’t equipped for IFR conditions. One of Genesys’ chief marketing points is that in the event of unintentional flight into IFR, a pilot using their system can prevent self-induced loss of control by simply letting go of the cyclic and allowing the helicopter to stabilize itself.
The Genesys product is made up of two parts: a stability augmentation system (SAS) and a two-axis autopilot. The Stability Augmentation System gets its data from a combination of the installed avionics and motion sensors located in the HeliSAS’s Flight Control Computer itself. When the controls are released with the SAS on, the helicopter will automatically attempt to return to a level attitude.
The HeliSAS adds trim force—called the “force feel” feature—that creates pressure on the cyclic to help avoid any accidental control inputs while the system is engaged. Though it works using electro-mechanical servo actuators, force feel essentially acts like a spring that keeps tugging the controls back to center. Center, in this instance, means stable flight attitude, not literal center-stick position.
Pressure from the force feel is present as long as the system is on, but it’s fairly easy for the pilot to manually override, if necessary. There are only about 3.5 pounds of trim pressure on the pitch axis and 3 pounds on the roll axis. There’s also an autopilot/SAS disconnect button on the cyclic for quick access if the pilot needs to turn either system off.
As with any autopilot, flying with the HeliSAS involves some attention to how the pilot is handling the controls. Too heavy a hand on the cyclic can unintentionally override the SAS input. A loose grip is important to allow the system to properly stabilize. When changing heading or altitude, there’s a Force Trim Release switch on the cyclic that can be activated to temporarily uncouple the force feel and allow for movement without additional control pressures.
The autopilot itself is a typical two-axis system, controlling pitch and roll. With the HeliSAS, the autopilot can’t be used without using the Stability Augmentation System, though you can use the SAS without autopilot. Sensibly, the autopilot can’t be used under 44 KIAS. Drop below that, and it turns off to prevent the system from creating a stall by trying to maintain altitude without being able to control power.
In terms of directional control options, the autopilot roll control can be set to turn to a heading and hold it. It can also be used to intercept and track nav-aids (back course, as well). Pitch control can be set to hold an altitude and for vertical navigation (ILS glideslope tracking, etc.).
Perhaps even more than LSAs, light helicopters need all of the load capacity they can get. In the case of the Genesys HeliSAS, 15 pounds is all you’re looking at adding to gain some fairly substantial controllability backups. Not a bad trade-off.
No system in aviation is complete without emergency protocols, and the HeliSAS is no different. There are several events that will cause the system to disengage without the pilot turning it off. Along with SAS and autopilot systems failures—tracked by internal safety monitors—the system will disengage with engine, drive train and hydraulic system failures. The system will also shut off at VNE –5 in order to make sure the pilot’s hand is on the controls if the helicopter’s speed begins to approach redline. If the system does turn off, an audible alarm will alert the crew.
New doesn’t always mean popular, but in the case of the Genesys HeliSAS, the numbers point to it being both. Given that it has no real competition yet, it isn’t much of a surprise that demand for the system is high. What’s surprising is just how high it has been. To date, Genesys has delivered more than 700 of the $100K HeliSAS systems.
Learn more at Genesys Aerosystems.