Pitot Obstruction Monitor - Aspen Avionics Evolution Backup Display EFD1000 Pilot's Manual

4.1.2. Pitot Obstruction Monitor

Most light aircraft have only a single pitot and static system available for flight
instrument use. As such, a common pitot and static input is shared between the EBD
and analog standby instruments. Should one or both of these pitot and static lines
become blocked, both the EBD and any standby airspeed and altitude indicators
could display erroneous airspeed and altitude information. Furthermore, because
the EBD uses pitot and static pressures as part of the AHRS attitude calculations, loss
or corruption of the pitot or static pressures can also influence the accuracy of the
displayed attitude information.
The EBD has been tested to be robust to these failures, either by being tolerant to
incorrect pitot or static inputs, or by detecting and annunciating a degraded attitude
solution. When connected to an IFR-certified GPS, the system is further able to detect
and annunciate blockages in the pitot system and will fail the attitude solution before
it becomes degraded. In that case, the system will red X the attitude and heading
information, and display a CHECK PITOT HEAT message as a reminder to the pilot to
check for ice accumulating on the pitot probe.
Once the system detects that the pitot obstruction has been cleared, the CHECK PITOT
HEAT annunciation is removed and the system automatically performs an AHRS in-flight
reset.
Should a GPS failure be experienced in flight, the Pitot Obstruction Monitor continues
to operate in a fail-safe mode and will continue to detect obstructions in the pitot
system that may occur while airborne. However, after landing, the monitor remains
active, and, as the airplane slows to taxi speeds, the system will indicate a failure of the
AHRS and annunciate CHECK PITOT HEAT. (Figure 4-8) In this circumstance, restoring
the GPS will restore normal monitor operation.
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Evolution Backup Display Pilot's Guide 091-00027-001 REV A
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