What Are Attitude and Heading Reference Systems?

In the realm of aviation, an attitude and heading reference system (AHRS) is an important element of many modern aircraft designs, allowing for attitude information related to roll, pitch, and yaw to be offered to pilots and flight systems alike for more efficient and safe operations. While some aircraft models achieve these readings through the use of inertial measurement devices such as gyroscopes, the consistent upgrades and advancements made to AHRs over the years has allowed them to be a very beneficial option that is compatible with flight deck displays, flight controls, and other such aircraft systems.

When discussing attitude heading reference systems, it is important to note that they are a singular package that comprises a number of inertial sensors like rate gyros and accelerometers. Oftentimes, an AHRS will also be paired with a flux valve or magnetometer, allowing them to determine the horizontal element of earth’s magnetic field while also ensuring the rate gyro can detect any yawing motions. With this combination of devices in a singular assembly, the AHRS can replace six separate line replaceable units for the benefit of highly reduced footprint, weight, wiring, and power requirements.

Beyond benefits such as lower weight and decreased power requirements, an AHRS can also provide increased performance when compared to conventional vertical and directional gyros. This is because of the cut off of automatic vertical erection that such gyros face when roll or pitch angles exceed certain values, leading to vertical errors. Gyros may also face errors when shallow bank angles are below the cutoff of the device, further proving the benefit of having an AHRS.

For a typical attitude heading reference system, an attitude heading reference unit (AHRU), flux valve or magnetometer, controller or panel-mounted switches, and a configuration module will all be common parts found within the assembly. Nevertheless, the exact types of sensors present will vary based on when the system was manufactured, who manufactured it, and other such factors. As technology continues to advance, AHRS internal components have progressively become smaller and more powerful.

Like many systems and assemblies, it is possible that you may run into various issues that require troubleshooting, making it important that you are aware of common issues and how to handle them. One common issue is area magnetic interference, that of which is when magnetometers and flux valves are influenced by the presence of large pieces of metal that disturb readings related to earth’s magnetic field. To avoid this problem, one simply needs to ensure that they avoid being too close to jetways, tow tractors, steel ramps, or other metal that may affect things. Aircraft magnetic interference is somewhat similar, though it refers to when errors are caused by ferrous meters being within a meter of the flux valve or magnetometer. Generally, this issue is easy to spot using a compass to see if the space is throwing off readings.

Beyond such examples, other common issues include errors in calibration, writing, or other such assemblies. Using manufacturer specifications and proper technique, remedying problems should be fairly simple. If you are conducting an inspection or maintenance and find that you need to conduct a replacement, rely on the experts at AOG Unlimited to help you secure all you require with competitive pricing and rapid lead times.

AOG Unlimited is a website belonging to the ASAP Semiconductor family, and we are unmatched in our ability to provide customers quick and budget-friendly solutions for their benefit. As you explore our various offerings, be sure to take advantage of our online RFQ service which will allow you to quickly and easily request quotes for your comparisons with team responses given within 15 minutes of receiving a submission. If you have any further questions or concerns regarding our offerings, be sure to give us a call or email at your earliest convenience, and we would be more than happy to assist you however we can!


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