Heading - Aspen Avionics Evolution Backup Display EFD1000 Pilot's Manual

In summary, loss or degradation of the EBD attitude solution is unlikely if the pilot
assures the proper operation of the pitot-static system. If the pitot or static system
becomes blocked, an ADAHRS internal sensor fails, or a CROSS CHECK ATTITUDE
indication is frequent or persists, the attitude indication on the EBD should be
considered to be compromised. In this case, the pilot must use the backup attitude
indicator for attitude reference until the cause of the problem has been identified and
resolved and normal system operation has been restored.

4.1.3. Heading

The EBD ADAHRS also includes a slaved compass system that provides accurate
magnetic heading indications throughout most operating conditions and phases
of flight. Its electronic gyros compensate for turning and acceleration errors, and its
remote fluxgate compensates for gyroscopic precession errors, so there is no need for
the pilot to adjust heading throughout the flight. Nonetheless, all compass systems are
subject to some error, and the pilot should be aware of when and how the EBD heading
indication can be affected.
The earth's magnetic field is measured directly by a 3-axis fluxgate magnetometer built
into the Remote Sensor Module (RSM), and magnetic heading is derived from the flux
on a plane perpendicular to gravity, providing immunity from pitching and rolling
effects. Electronic gyros and accelerometers in the EBD system are then used to stabilize
that raw heading data to eliminate the short-term turning and acceleration errors seen
in traditional magnetic compasses.
Together, these systems provide accurate heading indications even during aggressive
maneuvering. The gyros stabilize magnetic errors while maneuvering and are slaved
to the fluxgate, which continuously updates heading to compensate for gyroscopic
precession. The end result is a compass system that requires no pilot action to show
accurate magnetic heading throughout the flight.
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091-00027-001 REV A Evolution Backup Display Pilot's Guide
091-00027-001 Rev A EBD Pilots Guide V&H .indb 5 8/27/14 8:51 AM