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Tuesday, March 19, 2013

Cobham Takes HeliSAS Through Paces Over Vegas Desert

Rotor & Wing flew the autopilot system on a private Bell 407 during Heli-Expo in early March.

By Ernie Stephens, Editor-at-Large

Cobham, the avionics firm based in Mineral Wells, Texas, arrived at Heli-Expo 2013 with HeliSAS, the company’s sleek autopilot system specifically designed for the light helicopter market. Weighing in at a scant 15 lbs., the system, which was designed for Part 27-catagory helicopters in VFR conditions, is capable of providing hands-off flight for pilots across the pitch and roll axis. (Power and yaw remain the responsibility of the pilot.)

Edwards & Associates, Bell Helicopter's completions subsidiary in Piney Flats, Tenn., first installed HeliSAS in a Bell 206B. I was invited there to fly it in the summer of 2010 by Cobham shortly after its development and a few months before it received FAA certification. But I also accepted a second opportunity to see it perform over the desert outside of Las Vegas during Heli-Expo 2013. This time, it was installed aboard a privately owned Bell 407. (It is also certified for the 206B, and the Eurocopter AS350 and EC130.)

 

Demo Bell 407. Photo by Barry Schwartz

 

The control panel is trim, with activation buttons and corresponding LEDs for the stability augmentation system (SAS), heading hold (HDG), navigation mode (NAV), back course tracking (BC), altitude hold (ALT) and vertical navigation or “glide slope” hold (VRT). To keep the size, weight, and price down, it does not have the knobs or display windows found on standard autopilot consoles, with means you cannot dial in changes using the unit itself. Instead, it merely holds pitch and roll where the pilot had it upon system activation, or steers the aircraft to capture and hold a course dialed into the helicopter’s navigation system.

While not sounding like much when compared to a full-service, four-axis autopilot found aboard much larger and more expensive helicopters, HeliSAS does something most shopper pilots want to do once in a while: Take their hands off the cyclic and the collective for a bit to consult charts, open a bottle of water, or just take a stretch. Couple up the unit to the aircraft’s EFIS system—a Garmin G500, in this case—and if the helicopter’s attitude is disrupted within the envelope of plus or minus 5 degrees roll and within +11 and -6 degrees pitch, HeliSAS will return to within plus or minus 1 degree of the set attitude.

 

HeliSAS and the Bell 407 panel. Photo by Ernie Stephens

 

After takeoff from North Las Vegas Airport (VGT), HeliSAS was coupled up to hold altitude and heading. As advertised, I was able to sit with my hands in my lap as the system kept the aircraft on a heading 120 degrees, and an altitude of 4,400 feet MSL. Bumping the cyclic in any direct simply caused HeliSAS to self-correct without hunting. Of course, if you pull the aircraft into a 90-degree bank, the system will assume you want control back, and decouple itself. But generally, it earns the trust that most light helicopter pilots are hesitant to give to a little box.

Dialing in the ILS for Runway 12L at VGT and putting the system in SAS, NAV and VRT modes lined us up with the beams, and brought well past decision height. The only requirement from the human part of the system was to reduce power, adjust the pedals, and talk to the tower.
Related: Helicopter Avionics News

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