Another dash question...

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.

thanks

 

STBY Mode (Momentary Action) Pushing the STBY pushbutton has the following effects on the AFCS:
• No effect on AP/YD engagement
• Clears all active and armed lateral and vertical FD modes and removes FD command bars if the AP is not engaged
• Clears all active and armed lateral and vertical FD modes and FD command bars remain if the AP is engaged (Flight Director FDreverts to basic mode)
• Clears FD abnormal messages

 

Hey thanks...

question. Do you know this off the top of your head, or is there a resource I can find that has more information? Or did I just miss this information from the manual? Thanks

 

Sadly I know it off the top of my head.

This excerpt was copied and pasted from my flight manual since they said it in fewer words than I could. You probably missed it from the manual.

 

Most of the relevant information that can be used to answer your question comes from pg 7-2 of the SPZ-8000 manual. There's additional information that can be found in more detailed manuals from DeHavilland and Flight Safety. Both fortunately and unfortunately, Piedmont doesn't provide that level of technical detail anymore.

 

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.

 

I definitely was all over page 7-2. Searched the entire manual, the only explanation for STBY function is "Cancels all selected flight guidance modes." Ditto the systems manual. Gets kind of frustrating trying to find info that isn't there, especially when I know keeping my job depends on getting these questions right. More than a handful of questions that lack a direct/clear answer based on the material I've been given. Perhaps my resourcefulness is part of the test? Gonna look around the web for a Dehavilland or Flight Safety manual. Thanks for the help guys.

 

Another question, unrelated to the AFCS, what exactly the function of the hot battery bus? I'm seeing this bus in the CQT questions, but the manuals don't really say much about it, nor do the electrical schematics I have show anything. I read something about it being for a dome light and the fire bottles. Is it just a direct connection from the battery to these items? Or is it from the right essential? Also, is the APU fire bottle then connected to the hot battery bus?

PS : Am I right in saying the Lav does have fire protection in the form of a fire bottle in the waste container plugged with wax that melts to activate? No flight deck control other than a fire detect light?

 

The hot battery bus runs items that may need power while you are not there. On the -400 it runs things like the dome light, refuel/defuel panel, aft baggage light boarding lights and a few other items. All the hot battery bus items are connected directly to that bus which is powered by the standby battery.

The lav is exactly as described but there is NO indication in the cockpit.

Cargo fired...lost me on the hatch part and extinguisher. We are talking about different variants of the dash 8 so unfortunately some of this may not apply.

 

For the -100/-200/-300 what usmc-sgt said is mostly correct. Those items are wired to the "hot battery bus", but on the -100/-200/-300 the hot battery bus is powered by the main battery because there is no standby battery. That's why it's important to make sure the dome light and boarding lights are off when the aircraft is shut down for the night. Otherwise the main battery will drain and if the station does not have an operating GPU, there is no way to start the engines in the morning!

Essentially, yes. The battery master, main, and aux battery switches have no control over the power to the hot battery bus. For the sake of simplicity, just think of those items as being directly wired to the main battery. I think there is a row of circuit breakers either in the cockpit or on the DC contactor box in the nose compartment that represents the elusive "hot battery bus".

Yes, page 117 of the Piedmont systems manual. "The APU fire detector and the bottle are both hot battery bus, but owing to system design, the fire bottle will only automatically discharge if there is power to the essential buses."

Lavatory has a smoke detector that "emits a high pitched tone, and causes a red annunciator light, next to the flight attendant advisory light panel, to illuminate whenever the presence of smoke is detected inside the lavatory compartment."

Lavatory fire protection is for the trash container only, as if someone were to discard something that would ignite the paper products and such that were already in the trash. This is the fire bottle with the wax-type plug that you speak of, which will discharge when the temperature becomes too hot.

There is no flight deck control for the lavatory smoke detector or fire bottle in the trash container.

The "fire detect light" is a single light module in the lowest row of red warning lights on the caution panel. The "check fire detect" warning light only illuminates at the same time as the master warning, and directs the pilot to look up on the overhead panel to determine if the APU Fire warning light, or an Engine Fire warning light is illuminated. The lavatory smoke detection and fire protection have nothing to do with the check fire detect warning light.