Autopilot disconnect button

AlanR

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Joined
Jan 25, 2007
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175
Location
UK
Hi,
After 4years working just fine my Autopilot remote disconnect button has stopped working. The A/P works and disconnects just fine from the twin D1000's in the panel but not when I press the remote button.
When the button is pressed with the autopilot engaged I get a 'Pitch Slip' indication. If I press again the disconnect button I get 'Roll Slip' indication. If I then hold the button for a couple of seconds I get both a 'Pitch Slip' and 'Roll Slip' indication which then changes to 'Slip Trim Nose Down' indication but the autopilot does not disconnect.
Anyone had similar to this and thoughts on if this a Config problem in the D1000's or a Button Switch/Resistor problem?
My initial thoughts are that actual button must be ok or I wouldn't be getting any indications at all.

Thanks,

Alan.
 
Last edited:

airguy

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Nov 10, 2008
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Gods Country - west Texas
Reference section 3 of the installation manual, specifically pages 3-9 for how to enter Setup Mode, and 3-16 for the Autopilot Setup menu. This will give you some diagnostic data about what is happening with the servos and the disconnect button.
 

RV9APlane

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Joined
May 3, 2009
Messages
64
Location
Bakersfield, CA
Interestingly, I’ve had a similar issue recently. The AP disconnect button started not working intermittently and then all of a sudden my pitch servo stopped working or works erratically. I flew from Minneapolis to Bakersfield, CA yesterday with no reliable pitch control. 11.3 hours of grueling flight. I just started looking on here for ideas and saw this post, wondering if the AP disconnect button issue and my pitch servo issue are related.
 

kellym

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Sep 29, 2013
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Interestingly, I’ve had a similar issue recently. The AP disconnect button started not working intermittently and then all of a sudden my pitch servo stopped working or works erratically. I flew from Minneapolis to Bakersfield, CA yesterday with no reliable pitch control. 11.3 hours of grueling flight. I just started looking on here for ideas and saw this post, wondering if the AP disconnect button issue and my pitch servo issue are related.
Sounds a lot like you have a sheared pin on your pitch servo, regardless of whether you disconnect has a problem.
 

RV9APlane

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May 3, 2009
Messages
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Location
Bakersfield, CA
So I’ve been looking to purchase the servo shear screw kit, part #102991-000, and has available documentation but I don’t see any way to purchase it online. it doesn’t show up anywhere on the product search either. How do I get one?
 

kellym

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Sep 29, 2013
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So I’ve been looking to purchase the servo shear screw kit, part #102991-000, and has available documentation but I don’t see any way to purchase it online. it doesn’t show up anywhere on the product search either. How do I get one?
call support. IIRC they may not charge for it.
 

RV8JD

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Dec 17, 2017
Messages
334
I had a Dynon shear screw fail about a year and a half ago or so, on the SV-32 pitch servo in my RV-8.

Per Dynon, they adopted a stronger shear screw beginning late in the 1st quarter of 2017. It was adopted due to premature fatigue failures of the previous spec'd screw during normal use.

I called Dynon after verifying the shear screw had failed and they quickly sent replacement shear screw kits gratis (including one for the roll servo for if/when it fails). The kit includes the shear screw, an Allen wrench, a cotter pin, thread locker, and instructions for replacement.

Here is the way to check it:

1) Setup -> System -> Network Config -> Configure Run -> #8 Detect: Check to see that servos are in white lettering and say “Ready”.

2) In the hangar, turn on Autopilot. From outside the cockpit, gently move the elevator and aileron in each direction and check for resistance to movement. They should move just a little before you feel the resistance provided by the servos. If you can move the control surface a fair amount with little or no resistance the shear screw is sheared.

3) After the shear screw is replaced, redo the Servo Calibration. Setup menu -> Hardware Calibration -> AP Servo Calibration -> Calibration. Use slow and deliberate control movements.


Instructions for replacement:

https://www.dynonavionics.com/includes/guides/Servo_Shear_Screw_Replacement_Instructions_Rev_E.pdf

Video:

 
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AlanR

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Jan 25, 2007
Messages
175
Location
UK
Well...My problem as the original poster is definitely not the Shear screw as the Autopilot works just perfectly ok when controlled from the twin D1000's.
It is the Autopilot disconnect that is not working as it should.

It does not disconnect when the remote button is pressed but shows Pitch and roll indications.
I do not have at any time messages of 'Disconnect switch broken' or anything like that when the A/P is in operation.
After airguys's suggestion I have had a look in Config whilst in the hangar and all appears normal as regards settings and config. It shows disconnect button configured as it should but shows button not pressed. Pressing the button when not in A/P does not do anything but then I don't suppose it would anyway.
However, If I then put the A/P in 'Level', trying to simulate operating the A/P in flight, and press the disconnect button it still shows 'Button not pressed' but whilst still holding the disconnect button down it does stop the autopilot trying to level the aircraft and again shows the Roll and Pitch indications as before. (I did this in Config on P1 screen whilst viewing P2 screen) so could see that it showed 'Button not pressed' although pressing the button was clearly creating the indications on the Skyview.
So my conclusion so far is that the momentary disconnect button is working ok but somehow the Skyview is not responding and switching the Autopilot off from the remote button?....hmmm.
See pics showing config and shots of when the disconnect button is pressed showing Pitch/Roll indications.
I have emailed Dynon for their thoughts but whilst waiting for a reply any further thoughts on here would be appreciated particularly if someone has had the same or similar issue.

Thanks,

Alan.
 

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kellym

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Sep 29, 2013
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272
Two options. You can bypass the disconnect button by placing another in parallel, and see if you get different results with the temporary button...if so, the installed button is not making a good connection. Or you could check resistance across your button with it not pressed and with it pressed.
While you are getting some response when you press, the fact that the status screen shows it not pressed is pretty strong evidence that it is not making a good connection.
 

AlanR

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Jan 25, 2007
Messages
175
Location
UK
Two options. You can bypass the disconnect button by placing another in parallel, and see if you get different results with the temporary button...if so, the installed button is not making a good connection. Or you could check resistance across your button with it not pressed and with it pressed.
While you are getting some response when you press, the fact that the status screen shows it not pressed is pretty strong evidence that it is not making a good connection.

Thats a good idea..Thanks for that. The switch is mounted in the centre console and will be awkward to get to but I am sure I can rig something up temporarily without ripping everything apart just yet until I have a proper diagnosis.

However, just thinking.. If it is wire break or connection problem somewhere I would have thought though that I should be getting both audio and visual message 'Autopilot Disconnect Broken' which is the purpose of having the message system in Skyview if the disconnect is not working. Why am I not getting this message I wonder?
Having had both screens back to Dynon within the last 18months for 'Screen of death' problems my big fear of course is something electronic with Skyview not triggering the response...

Thanks again.

Alan.
 

RV9APlane

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May 3, 2009
Messages
64
Location
Bakersfield, CA
Sorry I hijacked your thread Alan, although I’ve had a similar problem which is what brought me to it in the first place. I removed my pitch servo today and the shear screw is sheared, will be calling Dynon in the morning. I’ll still have to figure out the disconnect issue. Thanks everyone!
 

AlanR

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Joined
Jan 25, 2007
Messages
175
Location
UK
Now in discussion with Don at Dynon about this but just to update this thread:-

Further to this..
I flew today 2 x 2.5hour flights today and the Disconnect button worked perfectly!....I must have pressed it a dozen or more times on each flight just trying to provoke it or make it not work and it worked just perfectly, disconnecting the A/P every time.
I was thinking along the lines of changing out the switch and the resistor but how it has worked perfectly ok today says to me that there is nothing wrong with the existing switch or resistor so I am not going to do that now.
I am now wondering if some sort of software glitch in my D1000 Skyview screens was the issue?
It just seems so strange that today it now works perfectly whereas the last 3-4 flights over a couple of weeks the problem happened every time the disconnect button was pressed.
I will see what happens next flight......


Alan.
 
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