Section 4 Reversionary Modes
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st
Ed Nov 2018
IDU-450 EFIS Software Version 8.0H (Rotorcraft)
4-5
Note 18:
Only DH function (with valid AGL altitude) in this mode.
Note 19:
Red-X in place of scale.
Note 20: VLOC CDI always available if optional VOR symbology
enabled.
Note 21:
Function removed during heading-only failure mode.
Note 22:
Rotorcraft versions (Part 27 or Part 29 airspeed scale), use full-
time large attitude bars and do not show the waterline symbol.
Note
23: Assuming valid fuel flow information, both range and
endurance are presented.
Note
24: Assuming valid fuel flow information, both range and
endurance are presented using inertial dead-reckoning based
on last known wind information. If the pilot is unable to dead-
reckon due to loss of heading or true airspeed cannot be
calculated, endurance only information is presented.
Note 25: Inhibited in accordance with the conditions specified in TAWS
automatic inhibit function (abnormal operation).
4.1.1. Oat Sensor Failure Mode
The EFIS has an OAT sensor failure mode. With the OAT sensor failed,
wind, OAT, density altitude, and true airspeed are not displayed on the ND.
4.1.2. Heading Failure Mode
The EFIS has a heading failure mode. With heading failed, the PFD
heading scale and MFD compass rose align with track (if available) or are
removed and replaced with a red-X.
The PFD heading scale includes “GPS TRK” around the track
marker to clearly indicate a heading failure mode.
Figure 4-1: GPS TRK
4.1.3. PFD Screen Auto Reversion
For IFR approval in aircraft, flight instrument information essential to safety
of flight remains available to the pilot without additional crewmember action
after a failure. To accommodate this, MFDs have the ability to sense when
the PFD has failed and take over the PFD function automatically.
Therefore, when an MFD (IDU #2, 3, or 4) becomes the transmit-enabled
IDU, the MFD automatically switches to the PFD screen. Push
to change
the MFD to other screens after the automatic switch.