Story ID: 346ArchangelHE15
Archangel Sensors Replace Costly Gyros
By: Matt Thurber
Caption: The company’s AHRS and ADAHRS sensors are available for a growing number of aircraft types.
Word Count: 517
Archangel Systems comes to Heli-Expo with a new certification achieved in December for its AHR150A and AHR300A air data attitude heading reference systems (ADAHRS).The company received European TSO approval for the sensors, allowing them to be used in small and large airplane and helicopter installations.

“This is Archangel’s first TSO outside of the U.S., and we’re pleased that is it on our flagship product,” said Bill Dillard, Archangel director of emerging technology. “Because the ADHARS are exportable worldwide, we get lots of interest from the European community. The ETSO really supports those customers and their programs.”

Archangel is expecting TSO approval of its AHR75 AHRS shortly; this unit doesn’t include the air-data sensors contained in the AHR150A and -300A. In the U.S., Erickson was the first customer for the Archangel ADAHRS, and the MD Helicopters MD902 Explorer with the Universal Avionics InSight flight deck will also use that system.

The key benefit of the Archangel micro-electromechanical systems (MEMS)-based AHRS is that it replaces traditional mechanical gyro-based instruments. The AHR75 weights five to 10 pounds less than a comparable gyro. “With a spinning-mass gyro, you have to have more spares on the shelf than with a MEMS-based AHRS,” Dillard explained. “There’s that dead capital of having spares on the shelf, you can’t do anything with that money and there is the ongoing refurbishment cost, maintenance, manpower to remove and replace and to oversee the refurbishment schedule.” In the rotorcraft environment, Archangel MEMS-base AHRS have a mean-time between failure of more than 12,000 hours.

The first customer for the AHR75 is Marenco Swisshelicopter, which is developing the clean-sheet SKYe SH09. Archangel has sent engineering prototypes to Marenco in advance of receiving the TSO. Some of the larger Archangel customers include Airbus military aircraft and Boeing rotorcraft. Upgrades using Archangel products are also available for the Bell 206 series.

Eagle Helicopters has flight tested the AHR75 in an Airbus AS350 upgraded to the Sagem ICDS avionics suite. “We want to add it to our STC,” said Eagle vice president Joe Rough. “We’ve been waiting for the TSO. It performed really well, and it’s a cost that people can digest fairly well.”

Eagle has done about 100 of the Sagem upgrades, but using the old Crossbow AHRS or an AHRS offered by Sagem. The Crossbow unit is no longer available for civil aviation applications, and the Sagem AHRS is designed for larger IFR helicopters with sophisticated autopilots, Rough said, “which is way overkill. We went to Archangel, they sent us a unit for testing and it’s performed really well.” This was especially true for a specific application, the Los Angeles Police Department’s desire to handle long-duration orbiting in a helicopter without losing orientation. “The LAPD had to go to Sagem [AHRS] because of their orbiting issues,” he explained. “Most AHRS won’t handle that, when they roll out, they roll over and die.” The Archangel AHRS handled that requirement without any problems, he said.