Thread: Dash 8 spz-8000 AFCS STBY
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Old 04-19-2011 | 08:05 PM
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trent890
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From: B787 FO
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Originally Posted by CentralPa717
In the spz-8000 manual, it indicates that the Standby will cancel the flight director...will the standby button also turnoff the autopilot? I have tried this on a dash 8 300 simulator on FSX, and flight director does cancel, and the autopilot also cancels, but does that necessarily mean the autopilot is off? Y/D continues to function. Any help is appreciated.
Testing your flight director/autopilot hypothesis on a FSX simulator may lead you to draw the wrong conclusions. I've found a couple of errors in how the electric and ice protection systems for the Dash-8 are simulated.

The Flight Guidance Computers (FGC) generate the Flight Director (FD) output that is displayed on the ADI. As a completely different issue, at least one Yaw Damper (YD) must be available in order for the Autopilot (AP) to be selected on and for the AP servos to move the elevator and ailerons in response to the FGC commands.

The primary function of the STBY buton on the FGC control panel is to cancel any flight director modes that are being generated by the FGC. Pressing STBY does not disconnect the YD or the AP. If the STBY button is pressed when the AP is off, the FD disappears from view on the ADI. If the AP is on, the FD reverts to a basic "wings level" and "pitch hold" mode.

The YD switch is a simple on/off switch to connect the YD to the FGC. As was said above, pressing STBY does not affect the YD in any way. If the YD is off, pressing the YD switch will turn on the YD but not the AP. If the YD is on, pressing the YD switch will turn off the YD, but it can also turn off BOTH the YD and the AP if the AP is on at the time.

Similarly, the AP switch is a simple on/off switch that powers the servos that allow the AP to manipulate the pitch and roll to satisfy the FGC commands. Once again, the STBY button does not affect the operation of the AP or YD. If the AP is off, pressing the AP switch will turn on BOTH the YD (if the YD was not already selected on) and the AP. If the AP is on, pressing the AP button will turn off the AP servos only. The FD will still be there, and the YD will still be on.
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