Issue getting Tow to work

[CJSouthern]

As I taxied in yesterday I saw a big open hangar and though "I'll park her in here for the night". When I tried to use the tow the plane just wouldn't budge; I've quadruple-checked that the parking brake is off - and even pumped the pedals to ensure that they're released. When I apply power to the tow in either direction it makes all the right noises, but the aircraft refuses to move ... and I briefly see a bit of "smoke" coming from both tyres.

So for all intents and purposes it's almost like it thinks the aircraft brakes are still on.

Any thoughts anyone?

 

[Goran_M]

That definitely should not be happening, and I just tested it on my end, and the tow does work.

If it happens again, can you post the TBM900_log.txt.  I'm suspecting something else is locking your brakes.

[aerox]

I tried the tow feature for the first time on the weekend and worked fine  

[CJSouthern]

Just tried it again and ... now it's working - so "who knows" what's going on. Perhaps it's a bit like that issue I had with the throttle not wanting to stay in high idle (either snapping across to flight idle or down to low idle); sometimes it does it - sometimes it doesn't - despite nothing appearing to change inbetween.

I noticed with the tow that if I leave the park brake off but toe brakes depressed then the tow won't let me move the "power lever" (it just snaps back to stop) whereas with park brake on and toe brakes off I can take the tow to full forward or reverse power (but obviously it doesn't move). When it wasn't moving I was still able to try full power in both directions so I assume that it thought it was the park brake that was on.

Not a biggie, but will post log if it does it again anyway.

[CJSouthern]

Can't get it to work again - here's the TBM log file & a video showing "brakes released" and "parking brake released" followed by "smoke from the tyres"

TBM900_Log.txt

[Goran_M]

I need the log.txt file.

[CJSouthern]

On 12/8/2020 at 4:29 AM, Goran_M said:

That definitely should not be happening, and I just tested it on my end, and the tow does work.

If it happens again, can you post the TBM900_log.txt.  I'm suspecting something else is locking your brakes.

 

1 hour ago, Goran_M said:

I need the log.txt file.

I'm confused. You asked for TBM900_log.txt do you now need log.txt as well?

[CJSouthern]

Got it to do it again - both logs attached.

 

 

Log.txt TBM900_Log.txt

[Goran_M]

I've just run a few tests and discovered something.  If you have throttle hardware, and it's set to control the power lever, it will also control the tow.  Full forward will push the tow causing the TBM to go into reverse and full back will pull the tow causing the TBM to go forward.

EDIT:  The throttle on your hardware will override the mouse when you try to move the slider.  So using the mouse will have no effect.

Edited December 12, 2020 by Goran_M

[aerox]

7 hours ago, Goran_M said:

I've just run a few tests and discovered something.  If you have throttle hardware, and it's set to control the power lever, it will also control the tow.  Full forward will push the tow causing the TBM to go into reverse and full back will pull the tow causing the TBM to go forward.

I can attest to this, it's how my setup works. I'm using my CH Throttle Pro (until my Honeycomb Bravo TQ arrives) to manage the power lever and it also manages the tow as well. 

[CJSouthern]

12 hours ago, Goran_M said:

I've just run a few tests and discovered something.  If you have throttle hardware, and it's set to control the power lever, it will also control the tow.  Full forward will push the tow causing the TBM to go into reverse and full back will pull the tow causing the TBM to go forward.

EDIT:  The throttle on your hardware will override the mouse when you try to move the slider.  So using the mouse will have no effect.

Yep - that's how it's always been for me (I didn't even know that I could use the mouse). The problem isn't that I can't get the slider to move - it's that the aircraft often doesn't move even when the slider is at one or the other extreme and making "lots of noise".

 

[Goran_M]

My guess is you have something holding the brakes, or the brakes are not actually off.  Are you sure you are pressing the foot brakes, turning the park brake off, then releasing the footbrakes, confirming they are released by checking their position, then trying to use the tow?

I have tested this, and checked with some other people running the TBM, and they are having no problems.

Even aerox, in the above post, seems to be having no problems.

[CJSouthern]

6 hours ago, Goran_M said:

My guess is you have something holding the brakes, or the brakes are not actually off.  Are you sure you are pressing the foot brakes, turning the park brake off, then releasing the footbrakes, confirming they are released by checking their position, then trying to use the tow?

I have tested this, and checked with some other people running the TBM, and they are having no problems.

Even aerox, in the above post, seems to be having no problems.

Not that I'm aware of; you can see in the video that I pump the brakes a couple of times - leaving them off - that the park brake is off - and yet I still get "smoke coming from the tyres". And in the very same video afterwards I was able to start the engine and taxi the aircraft.

Edited December 13, 2020 by CJSouthern

[Goran_M]

What happens if you do it on a hard surface/asphalt/concrete?

[CJSouthern]

Just now, Goran_M said:

What happens if you do it on a hard surface/asphalt/concrete?

Mixed results. Generally I only use it when I need to get the aircraft out of a tricky situation that I've got it in to; sometimes that's grass other times it's concrete (eg carpark -- don't ask ...). Somtimes it works just fine sometimes it won't.

Could it be that it THINKS the brakes are on if the friction coefficient is too high? (hence tyre smoke etc).

 

[Goran_M]

I'll have to confirm, but I think I remember that the tow is only to be used on hard surfaces.  I just tried it on a grass surface, and it wouldn't move.  The smoke isn't brake smoke.  It's "dust" from the grass/dirt.

[CJSouthern]

Thanks. I'll keep testing at this end.

[hiddenace]

I had the same issue tonight. Would it still tow with snow on the ground? 

[Goran_M]

On a hard surface with snow, probably.  On dirt or gravel with snow, no.

Edited December 16, 2020 by Goran_M

[hiddenace]

I was towing on concrete 

[gscottfuller]

I had a similar towing issue once and realized I had set the chocks when I parked! I assume that has been ruled out already.

[CJSouthern]

4 minutes ago, gscottfuller said:

I had a similar towing issue once and realized I had set the chocks when I parked! I assume that has been ruled out already.

Yep. From what I can tell, it mostly relates to the surface that it's on - or more specifically "the surface that it THINKS it's on" (I suspect that it thinks some surfaces have a higher friction coefficient than what us humans would assume to be the case).

Generally what happens is I'm looking at the aircraft from the front - use the throttle controls to control the tow power - tow device makes a noise proportional to the power setting - some "visible vapour" comes off the tyres momentarily - and nothing else happens. Goran said the "visible vapour" represents dust, but I'm not clear on why dust would come from a wheel if the aircraft was parked on grass / leaves and there was no tyre rotation.