Wiring the LG Box for BMS

[Tulkas]

I have one of gorgeous Albert's LG boxes, time to wire it for BMS.

The box has:
Solenoid +/-24V
Red Crystal +/- 5V
Permission switch (the one on the lever)
Switch LG down
Switch LG up

When I check the inputs BMS can take I only see UP, DOWN and EMERGENCY UNLOCK, which is purely mechanic in the box. I expected to have the PERMISSION SWITCH:


And regarding outputs, the bits I find in AIC are the solenoid, the red light, ok, and these two "Weight on wheels" which I don't know what to do with.

I expected to send a command to BMS with the "PERMISSION BUTTON" on teh lever and receive a solenoid output to unlock, but does not look to be the case. Someone knows what goes where?

Thanks

[jjbravo]

The permission switch is not simulated in BMS, it's internal to the landing gear box.
When the gear is up, the permission switch will activate the solenoid internally. When the gear is down, the solenoid is controlled by WOW.

  [ You are not allowed to view attachments ]  
  [ You are not allowed to view attachments ]  

[Tulkas]

The permission switch is not simulated in BMS, it's internal to the landing gear box.
When the gear is up, the permission switch will activate the solenoid internally. When the gear is down, the solenoid is controlled by WOW.

OK, Thanks, I think I understand... the basics of it at least, for physical execution I would need some more time.

The from Falcon (AIC) I only need the "gear handle (red)" and "MLGWOW" (main landing hear WOW?). What the "solenoid" and "NLGWOW" (nose I presume) for?

For inputs, I can just ignore the "AFEmergencyGearHandleUnlock", since this is purely mechanical in my box.

The permission switch will open the 24V circuit to the solenoid when the lever is up. When the lever is down, the 24V circuit will be already open until the WOW kicks in, which will close it again. I guess I don't need any relay since my output card can handle 24V?

Does this mean that the permission switch can override the WOW and retract the gear with the AC on the ground?

[jjbravo]

No, the permission switch is not in the circuit when the gear is down, so it doesn't do anything, as you can see in the pictures.
There are two circuits, one when the gear is down and one when the gear is up.

[Tulkas]

I see... my only problem with those diagrams is that I need the lgup and lgdown switches to send the input to BMS and here they are in the 24V circuit that would fry my xkeys... could I use relay switches also there?

[jjbravo]

Hmmm...keep in mind, this is the real gear panel, I don't know yours.
In this case, the 24V circuit is just for the solenoid, the diagram doesn't show the switch circuit, which is a different circuit you would attach to your xkeys (In my case my pokeys) and would indicate if the gear is up or down.

[Tulkas]

Well, my circuits I have to built from scratch, but I have the same elements, two switches to signal up and down, a 24V solenoid and a permission button.

But the switches are already installed, so I need them to signal up and down to BMS and at the same time.open and close the 24V circuit

[jjbravo]

Sorry, can't help you much there. I only have the real one and that's how I wired mine.

[salaxi54]

Well, my circuits I have to built from scratch, but I have the same elements, two switches to signal up and down, a 24V solenoid and a permission button.

But the switches are already installed, so I need them to signal up and down to BMS and at the same time.open and close the 24V circuit

I don't know how easy it would be in your case, but if they're SP switches, i'd replace them with DP ones, and have the one set of contacts to simply close the circuit for a signal, and the other set to provide 24V to the solenoid..

[AlbertJ]

@Tulkas

Sorry I missed your thread. I can help you with connecting the LG box.

Which version do you have? Are all the switches connected directly to the DB15 connector or is there a PCB inside the LG box?

[Tulkas]

@Tulkas

Sorry I missed your thread. I can help you with connecting the LG box.

Which version do you have? Are all the switches connected directly to the DB15 connector or is there a PCB inside the LG box?

Hi Albert, thanks for chiming in, I appreciate.

My box was not wired, I followed (a bit freely) the scheme you posted in another thread to wire it to a D-sub 15pin and therefore I started to investigate BMS functionality. I see I should maybe have had that second part clear before start wiring 



This is how I got it (not from you), it came with single pole switches for the UP/DOWN:



This is what I did:




 

[jjbravo]

With my setup the solenoid is just it's own circuit not connected to the gear up / down switches.
You should control the solenoid with a couple of relays connected to shared memory and the permission switch instead.
Then  just connect the gear up/down circuit to your xkeys.

See the diagram I posted.

[Tulkas]

With my setup the solenoid is just it's own circuit not connected to the gear up / down switches.
You should control the solenoid with a couple of relays connected to shared memory and the permission switch instead.
Then  just connect the gear up/down circuit to your xkeys.

See the diagram I posted.

Well, if I understand the diagrams correctly the up and down switched are in the 24V solenoid circuit.

But I want to do like you say, the switches just for the inputs.

My first post shows the AIC gives three outputs from BMS: MLGWOW, NLGWOW and Gear Solenoid. I think I need to know the logic these outputs follow inside BMS before I start designing my wiring.

[Tulkas]

Direct question about BMS, I hope someone can answer because I couldn't find the description of the different shared memory bits in the technical manual:

The "gear solenoid " bit


Does it include all the necessary logic? Activate (retract) the the solenoid when gear us down, release it when WOW...?

Then it'd be all I need, no need for the WOW bits, nor any relay. Just to connect the solenoid to my output, and insert the permission button with 24V in the circuit.

But I need to be sure what shared memory "gear solenoid " does.

[jjbravo]

I use the MLGWOW to activate the solenoid when the gear is down. (So if the MLGWOW is active, plane is on the ground and the gear is down the solenoid is not active)

You could probably just use the "Gear Solenoid", this will also indicates if the solenoid if broken. Sometime the solenoid could be malfunctioning if it burns out, so that is the benefits of using this shared memory. You will have to check if this actually indicated the status of the solenoid or just indicates if it's broken or not.