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Does G3X need flap position sensor for power to flap motor?

Desert Rat

Well Known Member
Here goes my G3X question of the day;

Does the GAD27 require a position sensor on the flaps in order to provide power to the flap motor?

I'm in the process of hooking up the secondary systems and I'm putting a meter on stuff as I get to that point so as to avoid any unpleasant surprises. I don't seem to have power to the motor wires but at this point but I don't have the position sensor hooked up yet either.

As we all know, this is the kind of thing that isn't easy to find in the book, so I thought I'd ask here.
 
yup I've got flap input power, to pin 5, and the switch pulls to ground on pins 7&8, but no current in either direction on the output ring terminals designated for the motor.

Started wringing out wires with no luck so far, but I started at the switch and am working my way backward.

Thanks for the response.
 
yup I've got flap input power, to pin 5, and the switch pulls to ground on pins 7&8, but no current in either direction on the output ring terminals designated for the motor.

Started wringing out wires with no luck so far, but I started at the switch and am working my way backward.

Thanks for the response.

Do you have pin#6 on the gad27 connected to ground? This is the ground for the flap motor.

Bill
 
yup I've got flap input power, to pin 5, and the switch pulls to ground on pins 7&8

Thanks for the response.

Pin 7 & 8 goes to the positive and negative on the actual flap motor….one to the positive and the other to the negative

Bill
 
Do you have pin#6 on the gad27 connected to ground? This is the ground for the flap motor.

Bill

Well, it's on the drawing that way :) I didn't build the harness.

Now that I know it likely isn't a config or sensor issue, I'll wring this out in earnest tomorrow. Odds are there's a pin pushed back or mis-located somewhere.
 
Pin 7 & 8 goes to the positive and negative on the actual flap motor….one to the positive and the other to the negative

Bill

oops, yeah, I said that wrong. Pin 7&8 are going to the motor. Pins 24 & 25 are switched to ground for flaps up & down
 
oops, yeah, I said that wrong. Pin 7&8 are going to the motor. Pins 24 & 25 are switched to ground for flaps up & down

Is it possible pins 7&8 on connector tb273 got mixed up with pin 7&8 on connector j271? Pins 7&8 on connector j271 are for power and ground for the gad27. When you power your system up does the green light come on on the gad27 indicating it has power?

Also pins 18 and 19 on connector j271 should be switched to ground for the flap motor operation. Pins 24 and 25 are switched to ground for the elevator trim


Bill
 
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Anything is possible. Witness my confusion tonight on these pin callouts. FYI- the reason I'm all over the place on this is that my interconnect drawing includes an Aux cannon plug that all this stuff pins into on the ship side, and the pin location on it isn't necessarily the same as when it reaches the other end of the line.

Anyway, thanks for all the good suggestions. I'll start chasing this down and report back.

When this is done, I think I'll start a "G3X Gotchas" thread. I've already started a list, of things that have tripped me up and where the answers haven't been readily apparent.
 
I'd probably start by looking at the device information page on the G3X display in config mode to see if the GAD 27 even recognizes that you are activating the flap switch.
 
If you want "manual" positioning and no flap info display you don't need sensors.

GAD 27 connects to the flap switch, flap power and flap motor.

Flap position is from sensor connected to GEA 24. I assume the CAN is used to broadcast position to whichever LRU is interested to listen...

You need flap position sensor you want pre-set positions, which can be managed by GAD 27 from GEA 24 input.
 
Victory.

Wanted to circle back to this with the solution.

When the avionics shop built up my main wire bundle, they terminated most everything that needs to mate to a stick button or panel switch in a 28 pin CPC connector.

The theory being that I could just pin the switches etc. into the open side of the connector, and the electrons would go their merry way to the GAD or wherever

In wringing this out, I discovered that they had missed 2 wires, specifically the ones that go from the CPC connector to pins 18&19 on GAD 271 to tell it to move the flaps.

I had wired my flap switch into the CPC correctly, but there was nothing on the ship side of those two pin positions from the CPC connector to GAD27-271 18&19. Pinned up two wires to those positions and all is well.

This is in no way meant to disparage my avionics shop. With all the wires running every which way in the fire breathing IFR monster I'm creating, I'm super happy that they only missed 2 wires in something as inconsequential as a flap controller.

Thanks to everybody who commented. All the input gave me a great place to start and saved a ton of head scratching, specifically wondering if I had a config problem vs. a wiring problem.
 
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