Nose wheel spinning at pushback end (Fenix)

[jgoggi]

Hi,
Looks like this happens to me only after the latest updates, but, most times, during pushback of my Fenix A320, when the ground agent tells me to set the parking brakes after pushback complete, the nose wheel starts spinning at high speed. This also causes the BRAKES HOT message.
Is this a known bug?
Thank you.

[virtuali]

The Hot brakes message is part of the Fenix internal simulation, and it should have been fixed with the latest update from Fenix.

The wheel spinning, if it happens ONLY with a Towbarless tow truck, might be related to having used different airplane payloads but also a possible change in the airplane modeling of shock absorbers, since GSX raises the front gear with different rates depending on the airplane model, with the Fenix having of course a custom value we tuned for it, but it might not be enough in some situations, so the wheel is basically scratching the ground.

Have you noticed it to be happening more when the airplane is a bit heavy ?

[jgoggi]

Hi Umberto,
Looks absolutely random, I tried the same situation (also same weights) and say 2-3 times it's ok. Then I try again and the wheel starts spinning. I realize because, with the ground roll option of FSRealistic set to on, the airplane starts vibrating (I also tried without FSRealistic but I get the issue as well). After that, as soon as the pushback disconnects, I get the BRAKES HOT message.
This both with the towbarless tug and with the towbar tug.
I am trying to understand what triggers this effect, but at the moment no success...

[jgoggi]

The first test I will do is trying at other airports, since the issue at the moment occurred only at Feelthere KLGA.

[virtuali]

The first test I will do is trying at other airports, since the issue at the moment occurred only at Feelthere KLGA.

Alright, if only happens on some airports, it might be related to either some altitude incoherencies in the scenery, as if the ground altitude is not where it's supposed to be. It might be also related to altitude differences happening on the apron itself, that might explain if it doesn't happen on all parking spots in the scenery.

[jgoggi]

Today I tried at Copenhagen by Flytampa and I get the issue. The strange thing is that, if I then exit and repeat the procedure, at times it works correctly and at times it doesn't.

[virtuali]

Today I tried at Copenhagen by Flytampa and I get the issue. The strange thing is that, if I then exit and repeat the procedure, at times it works correctly and at times it doesn't.

What do you mean with "exit and repeat" ?

- Exit from the sim ?

- Exit to the Main menu and going back to flight ?

- Restart Couatl from the tray bar icon ?

Restarting Couatl should always work, but if it doesn't, then the problem might be something in the sim, like Simconnect issues. In general, whenever something requires a simulator start and cannot be solved by just restarting Couatl, it's a simulator problem.

[jgoggi]

No difference between going to main menu or exiting the sim. Anyway I noticed something: when this happens, the main landing gear wheels don't turn during pushback and they are slightly lifted from the ground. This is due to the pushback tug connection, because before the tug connects, the wheels are perfectly on the ground.
Therefore, the problem seems to be that at times the airplane is slightly lifted off the ground when the tug is connected. The MLG wheels don't turn because the parking brake is on, but the NLG wheels are free to turn and they turn...


EDIT: It's incredible: when I do a serious flight from the beginning I get the issue. Then I do several pushbacks just to test the issue and can never reproduce it!

[jgoggi]

Any idea, Umberto?
Thanks.

[virtuali]

Any idea, Umberto?

Your screenshot would suggest the airplane contact points might not be exactly right, since GSX operates only on the plane pitch to raise the gear so, ideally, if the rear wheels contact points are exact, pitching the plane up should not affect the rear wheels.

However, if this was the case, it should happen every time, not just when you do a complete flight, whatever that means. Could be related to the airplane weight ? Can you test it using exactly the same weight ?

[jgoggi]

Thanks Umberto, I will try.
With "complete flight" I mean: I wake up a day and decide to do a flight. So I plan, do all the procedures and everything seriously. As soon as I push, I get that issue. After ending the flight (or quitting it, disappointed), I want to investigate and try again only the pushback phase or just before it... and nothing, all works perfectly...

[virtuali]

Does it happen only with Towbarless trucks, or even those with a Towbar ? I'm trying to understand if it's related to raising the front gear.

[jgoggi]

Even with a towbar.

[jgoggi]

Today I reproduced the issue again. This time the main wheels touch the ground and turn normally during pushback, but, as soon as the tug stops and I set the parking brake, the dance starts...
As soon as the tug releases, the landing gear struts instantly compress and the effect ends.
Below the links to some short videos and attached what happens to the brakes temperature after a few minutes...

https://www.dropbox.com/s/3fmuzrgfknixni4/WhatsApp%20Video%202022-11-19%20at%2013.09.42.mp4?dl=0

https://www.dropbox.com/s/5t722b7nl7ezygi/WhatsApp%20Video%202022-11-19%20at%2013.26.26.mp4?dl=0

https://www.dropbox.com/s/a16nlizupnqphsb/WhatsApp%20Video%202022-11-19%20at%2013.26.32.mp4?dl=0

https://www.dropbox.com/s/sfm310cqklvi8fu/WhatsApp%20Video%202022-11-19%20at%2017.01.28.mp4?dl=0

[jgoggi]

Maybe I have found out!

It depends on the wind! I started the pushback with zero wind and, after the tug stopped at the end of the pushback, the nose wheel did not move at all. Then I increased wind speed and, as soon as I went up with the slider, the wheel started spinning like mad! I then moved the wind speed slider back to zero, but the wheel kept spinning....
So if there is a certain wind, when the nose wheel is raised, it kinda feels the wind and starts turning...