4 AXIS FLIGHT DIRECTOR - OPERATION
ENGAGING AND DISENGAGING FD MODES
Flight Director modes are engaged and disengaged via the Guidance
Controller (FD Control Panel). Each mode pushbutton green light illuminates
when the mode is armed or engaged (captured).
The engagement of the FD modes is made with the Guidance Controller
(GC) and the communication to the AIOP modules is through the CIO
modules.
Each mode may be deselected by pressing the associated pushbutton on
the Guidance Controller.
All engaged modes may be deselected simultaneously by using the STBY
button on the Guidance Controller or the FD STBY button located on pilot or
copilot cyclic stick grips.
GA (Go Around) mode can only be engaged by using the GA button on pilot
or copilot collective lever and disengaged by engaging a different vertical
mode or setting FD to STBY.
Armed and captured FD modes are displayed with messages along the top
line of the PFD:
• collective and pitch mode messages on the left
• lateral mode messages on the right
Armed modes are shown in white small font; captured (or engaged) modes
are shown in green medium font.
When transitioning from no mode to engaged, from armed to captured or
change from one mode to another mode a chime sounds and the message
flashes normal/reverse video for 6 seconds then becomes steady (normal
video).
When changing from captured (or engaged) to no mode a chime sounds and
the message flashes on and off for 6 seconds then extinguishes.
Pitch and roll command bars and/or collective cue are displayed on the PFD
by the AFCS when a Flight Director mode is active on the relevant channel.
When there is no FD mode active the command bars/collective cue are not
displayed.
When HOV mode is the active flight director mode, the pitch and roll
command bars are not displayed.
All modes are disengaged when toggling the PFD button on Guidance
Controller, ie STBY pushbutton illuminates.
All modes - except HOV, ALT and RHT - must not be engaged below 60
KIAS and are automatically disengaged when airspeed reduces below 55
KIAS.
HOV mode can engaged between 0 and 75 KIAS and groundspeed within
60 Kts forward or 40 Kts lateral or aft.
ALT and RHT can be engaged between 0 KIAS and Vne.
All modes have a Minimum Use Height limit: see RFM Supplement, Section
1 – Limitations.
FD COUPLING AND UNCOUPLING
When a FD mode is engaged (captured) the coupled (CPL) function is also
automatically engaged if the AP is in ATT mode and the relevant Force Trim
is engaged: the CPL pushbutton green light on the Autopilot Controller
illuminates.
When coupled, both autopilots drive their actuators to satisfy the references
provided by the priority FD.
Selecting a FD mode by pressing the pushbutton on the Guidance Controller
with ATT OFF (i.e. SAS mode or both Autopilots off) will engage the FD in
the Uncoupled mode.
The FD may be manually uncoupled by pressing the CPL pushbutton on the
Autopilot Controller when illuminated: the CPL green light extinguishes and
the UCPL annunciator appears on both PFD’s; on the ADI the command
bars and/or collective cue remain in view and the pilot can manually fly the
commands.
When the AP reverts to SAS no UCPL caption will appear on the PFD.
In either case (Coupled or Uncoupled) pitch, roll command bars/collective
cue are presented on each PFD, depending on the mode selected.
The coupled function is also automatically forced to Uncoupled whenever:
• the AP is not in ATT Mode
• moving the CLTV/YAW TRIM switch to OFF when a collective FD
mode is engaged
In case of single AP operation, when a FD mode is engaged the coupled
function remains available.
Autopilots ignore the FD commands when pilot flies the helicopter manually
against any artificial feel device while the FD is coupled, because of the