Archangel Systems has implemented a strategy of making its attitude and heading reference systems (AHRS) and air data attitude and heading reference systems (ADAHRS) compliant with civil regulations as well as military standards for environmental performance and software certification. This dual-use commercial off-the-shelf (Cots) strategy will benefit military programs that rely on the products, especially the U.S. Department of Defense’s Joint Vertical Lift Initiative, which could see the life of the 50-year-old CH-47 Chinook extended through 2060, according to Archangel Systems. Other dual-use applications for Archangel products include Sikorsky Black Hawks and Bell Helicopter programs from Hueys to others under development.

Both the company’s AHRS and ADAHRS meet civil RTCA DO-178 and DO-254 software and firmware development standards, but Archangel also complies with Design Assurance Level A (DAL A), which the company said is “reserved for mission-critical systems where failure could be catastrophic.” 

According to Bill Dillard, Archangel director of sales and marketing, the company “is seeing strong growth in dual-use contracts for AHRS and ADAHRS, both here in the U.S. and internationally. When we first established our code-development protocols, we chose to be DAL A compliant. That decision has proved valuable despite the additional labor and independent verifications DAL A requires. Using DAL A as our day-to-day software-development protocol gives us another advantage. Military customers are more interested in certification artifacts than TSO approvals. DAL A processes inherently generate the expected evidence.”

Archangel also certifies its products to the highest categories of DO-160 environmental performance standards, which benefits military operators of aircraft flown in harsh environments, especially aircraft made with composite airframes. “Our dual-use customers have found those certifications adequate for their uses,” Dillard said. “This allows us to reuse [intellectual property] without retesting. The customer gets a product with shorter lead time and pricing. When a customer requires tests not covered by DO-160, such as gunfire, rapid decompression and elevated temperature, we retest per corresponding MILSTD protocols.”

Archangel can add features to Cots products, such as a heading preset function to the AHR150A ADAHARS. “While the main goal is delivering the required performance, we try to effect new features, particularly software, by independent modules that can be reused without recertification,” he said. 

Security of Cots products is an issue for military aircraft, and according to Archangel, “it can be developed either within DoD standard practices [still in planning] or proactively independent.” Archangel allows two proactively independent configuration methods for its ADAHRS. A software application makes configuring the ADAHRS a more flexible process, while the highest security is available via pin strapping, which “eliminates external computer access to the ADAHRS during the configuration process,” Dillard explained.