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mherzog

nosedive with autopilot on during flight after mouse click in cockpit is performed

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This may be a difficult issue to resolve at this point as I have not found a pattern.  But if this isn't a known issue, I'd still welcome any troubleshooting ideas

 

The problem itself is the following:

At some point in the flight I will click something in the cockpit of the 737 and then the autopilot will stay on but the nose of the plane will point straight down and I must disengage the AP.  After recovery anytime I select the AP again (either R or L) the nosedive will occur. I have looked for failures in the FMC and there are none.

 

I can turn off VNAV and only use LNAV with AP and it will work.  However, if I swap to any of the vertical AP options (VNAV or V/S) it will nose dive again.

I am able to level off and use Alt Hold at a given altitude(sample size of 1).

 

I can give you a few examples of when it has happened (and I will add more as when it occurs again):

  • Clicking the Weather button on the EFIS to display weather
  • Clicking the STD button on the barometer while descending below FL180
  • Clicking the copilot yoke pedestal to lower it.
  • Descending through FL330, it was either when I was twisting of the NAV1(ILS) freq or (more likely) when I clicked the "swap freq" button to make it active

This has only happened since updating to 3.4 (P3D) sp1 and this does not happen on every flight.. maybe 1 in 4 or 1 in 5, I'd guess.

 

 

I believe (but cannot be certain yet), that I have always been on the descent part of the flight when the issue occurs.

 

Is there anywhere else I can look (logs, etc.) that might suggest what made it decide to nosedive?  

 

I am using:

  • P3D 3.4 SP1
  • PMDG 737ngx 800/900  -- OC says it's up to date
  • FSUIPC is the most recent version that has been updated for 3.4 sp1
  • AS16 + ASC (beta versions that are setup for 3.4 sp1)
  • Ultimate Traffic2 (newest version they uploaded there a couple months ago)
  • and a few other addons, that I can list if you feel they could be in play.

 

Thanks for any ideas,

Mark Herzog

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is there any chance you accidentally engaged, via right click, the mouse yoke function? in which case as soon as you move the mouse to go click somewhere,  the AP thinks you are doing an emergency intervention and the plane AP disingages and dives?  doesnt really fit that well with your description but just a thought....

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Thanks for the idea.. but I don't think so.. in that case I should also get the AP failure in the FMC (not sure what it's called, but it's the result of "shearing of the bolts" in the AP mechanism)... and in that case you should also still have the ability to use the CMD/R Autopilot, but in my case, after the initial failure, any sort of vertical AP feature causes a nosedive

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Thanks for the idea.. but I don't think so.. in that case I should also get the AP failure in the FMC (not sure what it's called, but it's the result of "shearing of the bolts" in the AP mechanism)... and in that case you should also still have the ability to use the CMD/R Autopilot, but in my case, after the initial failure, any sort of vertical AP feature causes a nosedive

 

Do you have a trim axis on your hardware? If so, have you ensured that it is centered prior to engaging the AP? Make sure to check. Any time you install the sim (potentially when you update it), your assignments can be reset, and FSX and P3D like to assign something to every button and axis on your hardware.

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Thanks for tip, I will check this when I get home this evening.  But, just off the top of my head (not in front of sim to confirm), when I bump my normal trim axes (on my yoke), it causes AP to disengage.... wouldn't that be the case with your suggestion as well?  In my situation the AP actually stays on... it just nosedives.

 

Mark

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 In my situation the AP actually stays on... it just nosedives.

 

Sounds like a bad CMOS battery then.

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Weird... I never thought of that ...but I suppose that could be the case, if the low voltage is messing with the bios clock... desktop is about 4 years old.   I will see about getting into the case and testing the battery this weekend.

 

I'll also make sure my BIOS is up to date, and try to test it more this weekend.

 

Thanks for the suggestion,

Mark

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