-GO AROUND mode.
In these cases, the AP1 has priority and is active. The AP2 is in
standby and becomes active if the AP1 is lost.
When these modes are released, the AP2 is disengaged automatically.
The AP can be engaged on the ground in any mode with engines stopped.
The AP disengages when one engine is started.
An AP can be engaged again 5 s after lift-off in active FD modes (if
at least one FD is engaged) and, in HDG and V/S modes (if no FD is
engaged).
At AP engagement, the load thresholds on the side stick controllers
and on the rudder pedals are increased.
AP engagement is indicated by the illumination of the corresponding
pushbutton switch (three green bars) and by the AP1 or AP2 indication
in the status column on the PFDs.
The pilot can disengage the AP in different ways:
-
By action on the engagement pushbutton switch, with the green bars on.
-
By action on one takeover and priority pushbutton switch on the
side stick controller. Loss of the AP is indicated by an aural and visual warning (Ref. para. 2. B. (6).
(2) AP ENGD Hardware Logic
(Ref. Fig. 010)
(a) Principle A part of the AP engage logic is accomplished through the hardware. It takes into account the following signals:
-AP ENGD boolean generated in the software
-FG HEALTHY logic signal (Ref. para 2. A. (2))
-AP SW wired discrete from the FCU.
The AP ENGD hardware logic utilizes the command and the
monitoring channels. Each output discrete takes into account the
conditions generated by each generated by each channel.
During the safety tests (at power rise) the AP SW signal is
inhibited prohibiting engagement through the pushbutton switch.
The disengagement takes place in the hardware logic:
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-Upon loss of one of the AP ENGD and FG HEALTHY signals after confirmation of 200 ms.
-Through action on one takeover and priority pushbutton switch located on the side stick controllers.
-Upon detection of long power failure (LPF) by the power unit.
In the event of short interruption, the engage signal maintains
its pre-cutoff state. The final circuits are therefore supplied
with back-up current (VS).
They are isolated from the other signals during the cutoff (SW
RESET signal active).
-
The AP ENGD wired discretes obtained are used by : the FACs (selection of AUTO mode and acquisition of yaw axis guidance signals)
-
The ELACs (selection of AUTO mode and acquisition of guidance signals, pitch and roll axes and nose-wheel steering)
-
The FCU (illumination of the corresponding AP pushbutton switch, 3 green bars, and selection of the FMGCs (generation of the AP warning)
-
The opposite FMGC (disengagement of associated AP if in cruise modes, selection of the FMGC having priority)
-
The OWN FMGC (engagement wrap around).
(b) AP ENGD Software Logic
1_ Engagement conditions
This signal is at 1 (flip-flop set) if all the engagement
conditions are activated:
- Action on the engagement pushbutton switch
- Ground conditions : engagement possible in any mode only if
the engines are shut down
- Flight conditions : engagement possible 5 s after lift-off
- Conditions specific to the AP : AP COND (Ref. para. 2. B.
(5)
- Conditions common to the AP/FD : AP/FD COND (Ref. para. 2.
A. (3)
- Conditions common to the AP/FD and A/THR : AP/FD/A THR COND
(Ref. para. 2. A. (4).
2_ Disengagement conditions
This signal is set to O (flip-flop reset) when a disengagement
condition is present:
- Action on the engagement pushbutton switch, the associated
AP being already engaged
- Engagement of the opposite AP if the AP is not in LAND or GO
AROUND mode
- Action on one takeover and priority pushbutton switch
- One engine start on the ground
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AP - Engage Hardware Logic
Figure 010
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1
-Loss of one condition : either AP COND, or AP/FD COND or AP/FD/ A-THR COND
-In the event of landing in dual-AP operation, disengagement of AP2 only when the LAND or GO AROUND mode is released.
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