Wiring the LG Box for BMS

[Tulkas]

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)

Does the MLGWOW sends signal on/off when the gear is down? Let me explain:
-We are airborne gear up, MLGWOW does nothing, solenoid unpowered, lever locked. Push button to unlock.
-Airborne gear down, does MLGWOW now send a off signal to keep the solenoid powered-lever unlocked?
-On the ground, gear down, MLGWOW sends on signal, solenoid unpowered, lever locked

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.

This all I found about that shared mem bit:

[jjbravo]

No, MLGWOW is "Main Landing Gear Wight On Wheels", so as soon as you lift off even if the gear is down it will turn on.
Which is what you want so you can raise the gear.

[AlbertJ]

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?

Yes, you could use two relays to keep both circuits seperate. One circuit for the solenoid, and one for connecting to your X-keys. Another solution would be to add two more of the exact same up/down switches, and stack them inside the LG box.
This last solution is what I did in my LG box some time ago when I was adding the DN Lock release switch. This keeps it all very simple in my opinion.

The best is to use the ''Gear solenoid'' function in AIC for your solenoid circuit. This way you can also reverse the solenoid, and use the delay, which is very welcome to have. I have set my gear solenoid delay to 1.0 sec. to prevent
stuttering of the solenoid when landing.

[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?

Yes, you could use two relays to keep both circuits seperate. One circuit for the solenoid, and one for connecting to your X-keys. Another solution would be to add two more of the exact same up/down switches, and stack them inside the LG box.
This last solution is what I did in my LG box some time ago when I was adding the DN Lock release switch. This keeps it all very simple in my opinion.

The best is to use the ''Gear solenoid'' function in AIC for your solenoid circuit. This way you can also reverse the solenoid, and use the delay, which is very welcome to have. I have set my gear solenoid delay to 1.0 sec. to prevent
stuttering of the solenoid when landing.

Thanks Albert, I think I will follow your advice and try to place extra switches.

I was doing some experimenting with the AIC "Gear Solenoid". I felt I needed to be 100% sure of what it does before I start to make the circuits. It turns out that the AIC "Gear Solenoid" bit is basically a MAIN GEAR WOW SENSOR:

https://www.youtube.com/watch?v=yieN8hnY8S4

So the solenoid is powered all the time except when the three wheels are on the ground. That means I have to break the circuit when the gear is up, to unpower the solenoid, and then close the circuit with the permission button so I power the solenoid and I can lower the gear

[jjbravo]

So the solenoid is powered all the time except when the three wheels are on the ground. That means I have to break the circuit when the gear is up, to unpower the solenoid, and then close the circuit with the permission button so I power the solenoid and I can lower the gear

That's how the real one works.

[Rufus]

...I wonder about that - I've read somewhere about pilots wearing out the solenoids in the Gear Handle continually pressing the button like it was a fidget spinner, to hear it click just as a matter of passing time - and that tends to wear them out.  That couldn't happen if the solenoid were actually de-energized.  I think I'll have a look at the Dash-1...

There is a saying among Test Pilots I've known that one should "only touch the shiny switches";  i.e. - the ones most used.  I had charge of installing the first RECCE system in an F/A-18D, and when I finally installed the system in the jet I noticed that the switch on the control panel in the cockpit was shiny...even though that switch had been connected to absolutely nothing for years prior.  So I know that crews do tend to "fidget".

[Tulkas]

So the solenoid is powered all the time except when the three wheels are on the ground. That means I have to break the circuit when the gear is up, to unpower the solenoid, and then close the circuit with the permission button so I power the solenoid and I can lower the gear

That's how the real one works.

Yes, but I thought -or hoped- that that logic would be already in the shared memory bit 

- I've read somewhere about pilots wearing out the solenoids in the Gear Handle continually pressing the button like it was a fidget spinner, to hear it click just as a matter of passing time - and that tends to wear them out.  That couldn't happen if the solenoid were actually de-energized.  I think I'll have a look at the Dash-1...

I think was Nígel the first one to mention it after hearing from an ac grond crew but I always had problems picturing a bored F16 pilot messing around with the landing gear consent button at FL300 0.85M 

As I understand the solenoid is de-energized gear up, it energies when you push the consent

[Rufus]

...so now I'm a bit confused by what we think we really mean by "de-energized".  To me this would/should imply there is no power to the solenoid.  If it is a down lock over-ride meant to to be used in an emergency, that would/should imply that it is always "energized" (i.e.; would function) gear up/gear down if the Gear Handle were to jam/stick...but the distinction as to what the gear actually do would be the position of the Gear Lever itself.

It's the WOW switches that will keep the gear from retracting on deck...but I'm thinking that the solenoid switch and power are always hot.  I seem to recall that this is how my Pegasus LG box functions, and the rest of the logic is handled by BMS itself.

[Tulkas]

...so now I'm a bit confused by what we think we really mean by "de-energized".  To me this would/should imply there is no power to the solenoid.  If it is a down lock over-ride meant to to be used in an emergency, that would/should imply that it is always "energized" (i.e.; would function) gear up/gear down if the Gear Handle were to jam/stick...but the distinction as to what the gear actually do would be the position of the Gear Lever itself.

It's the WOW switches that will keep the gear from retracting on deck...but I'm thinking that the solenoid switch and power are always hot.  I seem to recall that this is how my Pegasus LG box functions, and the rest of the logic is handled by BMS itself.

Well as I have understood and the others owning the real thing appears to confirm, solenoid energised means lever unlocked, so there are three situations:

-gear up. Solenoid de-energised. Lever locked. Push consent button to energise solenoid and unlock lever
-gear down and airborne. Solenoid energised. Lever unlocked. You can raise the lever. No need to push the consent
-gear down and on ground WOW. Solenoid de-energised. Lever locked. Consent button de-energised. Not possible to rise the lever

And the you have the mechanic override which physically push the solenoid to unlock the lever. I suspect that even you lift the lever with the override if you have WOW landing gear will not retract? But I leave that to BMS logic

[Rufus]

That all makes sense, but to someone like me that wires RL jets the use of the word "energized" carries it's own engineering meaning - in my world "energized" means the circuit still has live power flowing through it - which in the below case is true, button pressed/not and lever locked or not...hence my confusion.  But no matter what the lingo, they make it work... .

I've had to do on-deck procedures on a few occasions where I have had to raise the gear handle in a jet on deck...which I admit, has bee scary every time I've done so, but there are Maintenance actions which require that. But having the gear pinned will stop the gear from moving - the only time I've ever had to actually allow the gear to move was with the aircraft on jacks...which was even move scary!

[jjbravo]

-gear up. Solenoid de-energised. Lever locked. Push consent button to energise solenoid and unlock lever
-gear down and airborne. Solenoid energised. Lever unlocked. You can raise the lever. No need to push the consent
-gear down and on ground WOW. Solenoid de-energised. Lever locked. Consent button de-energised. Not possible to rise the lever

That is correct.

BMS will not simulate the permission switch as you can't really do that in BMS, it makes more sense that you handle this in the gear box itself.