B1900 lights question

[Groundpounder]

I was looking at a picture of the overhead panel of a B1900D, and for the beacons, there is a flight and a ground position, along with the off position. What is the difference between ground and flight settings for the beacons?

The pic:
http://www.jetphotos.net/viewphoto.php?id=177109

Thanks.

 

[CA1900]

The only difference is what bus supplies the power to it. In ground position, it gets power any time the battery is engaged. In flight position, it only gets power when one of the generator busses is powered (I forget which one), meaning that in the event of a dual generator failure, it will automatically shut off to save battery power.

The ground position is there mainly so you can power the beacon prior to engine start. Once an engine is running and that generator is engaged, the switch goes in flight position and generally stays there until the airplane is parked at the gate and the engines shut down. That will automatically shut it back off, again to conserve battery power.

Hope that helps.

 

[cpt190]

On the 1900D, in ground position, both the upper and lower beacon flash, in flt position, just the bottom beacon flashes.

 

[chperplt]

On the 1900D, in ground position, both the upper and lower beacon flash, in flt position, just the bottom beacon flashes.

You sure about that?

 

[CA1900]

You sure about that?

It's not the case on our airplanes at CommutAir, nor the 30 we traded in a few years back. All of those operated as I described above. Maybe theirs are custom-wired or something? (Although for the life of me, I can't think why you'd want to shut off the upper beacon in-flight.)

 

[Marko Ramius]

As the other poster said, the only difference is the power source. GND is center bus, and FLT is left gen bus.

 

[Typhoon1244]

Since you brought up the 1900, a brief irrelevancy, if I may: why do the exhaust stacks point in cockeyed directions?

 

[chperplt]

if I may: why do the exhaust stacks point in cockeyed directions?

It's to make putting the prop tie downs on harder.

 

[socalpilot]

What's a prop tie down? j/k The exaust stack is pointed away so you don't melt the windows out. When the power is in ground fine there is no airflow from the props to move the warm air away and apparently they had a problem with the windows melting before.

 

[Cardinal]

Fuselage heating is an entirely different matter - that's the cause of the limitations on the use of Ground Fine while stationary and the 3 minute limit in feather (at least at Lakes). The rightside exhaust stack on each nacelle is pointed upwards and elongated to counteract the natural swirl in the propwash, otherwise the descending airflow behind the descending blade would direct the exhaust directly onto the wing and boot - no bueno.

 

[socalpilot]

The rightside exhaust stack on each nacelle is pointed upwards and elongated to counteract the natural swirl in the propwash, otherwise the descending airflow behind the descending blade would direct the exhaust directly onto the wing and boot

That makes sense when I think about it. I was just repeating what a check airman told me but I think I like your explanation better.

 

[Typhoon1244]

I was just repeating what a check airman told me...

Well that was your mistake right there!