Autopilot Problem

SoCal 182 Driver

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Sep 11, 2019
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SoCal 182 Driver
Avidyne IFD 540, dual G5s, and AeroCruze 100 (TruTrak) autopilot.

I had a problem with my autopilot today. No matter what I did, or how many times I baro-synced, it wanted to climb. This occurred both when working off the G5 for heading and altitude, and also in GPSS mode, with altitude set on the autopilot itself. Altitude was 10,500'.

I tried baro-syncing several times, but no joy. I tried trimming the plane manually, with the autopilot off, and then engaging the autopilot. No joy. I tried shutting down the autopilot and restarting. No luck. No matter what I did, the plane wanted to climb. And, while climbing, the autopilot would be asking for up trim.

Any thoughts on what might be causing this?

Advice and comments appreciated.
 
Static leak, both the autopilot and the G5 have a connection. When was the last IFR/Pitot check?
 
Static leak, both the autopilot and the G5 have a connection. When was the last IFR/Pitot check?
I'd have to double-check, but I think I have about another year before I'm due for another check.
 
Static leak, both the autopilot and the G5 have a connection. When was the last IFR/Pitot check?
This got me thinking. If I had accidentally activated the alternate static source switch, could that have caused the autopilot behavior I experienced?
 
Admittedly, I am not an avionics expert, but if the pitot-static system was functioning properly, and I accidentally activated the alternate static source, wouldn't that essentially be opening a leak to the pitot-static system?
 
My older STEC 60-2 AP has dedicated static ports in the rear, so no connection to OEM ship’s pitot-static system. How is your AP connected?
 
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When you had it in GPS mode. What did the autopilot show for an altitude?
 
When you had it in GPS mode. What did the autopilot show for an altitude?
When in GPSS mode, I set the altitude for 10,500' on the autopilot control head. The plane would continuously want to climb above 10,500', and in the process the autopilot was asking for up trim.
 
When in GPSS mode, I set the altitude for 10,500' on the autopilot control head. The plane would continuously want to climb above 10,500', and in the process the autopilot was asking for up trim.
If you push the right-side button twice it will show you what altitude the autopilot thinks it’s at. Its where you set the altimeter if you are in GPS mode. Just curious if the altitude matched your pre-selected altitude? did the control unit say "alt hold" ?
 
By the way. My TruTrak had an issue holding altitude when it was first installed. It would overshoot and begin to porpoise. I worked with some other 182 guys that were experiencing the same issue. These are the numbers we are running now, and everything has been fine for the last 4 years running these numbers.
*** The chart shows 182RG but those numbers work perfectly in my fixed gear 182P
 

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If you push the right-side button twice it will show you what altitude the autopilot thinks it’s at. Its where you set the altimeter if you are in GPS mode. Just curious if the altitude matched your pre-selected altitude? did the control unit say "alt hold" ?
That's how I baro-sync the autopilot to the altitude shown on the G5. They were within 50' of each other, and when I would sync, they would be within 10' of each other.

Yes, the control head did say "alt HOLD," but it wanted to climb regardless.
 
By the way. My TruTrak had an issue holding altitude when it was first installed. It would overshoot and begin to porpoise. I worked with some other 182 guys that were experiencing the same issue. These are the numbers we are running now, and everything has been fine for the last 4 years running these numbers.
*** The chart shows 182RG but those numbers work perfectly in my fixed gear 182P
I've had the TruTrak for over a year, and it's been pretty solid. As recently as the day before the flight in question, I flew for two hours at various altitudes assigned by ATC, and did not have a problem with climbing. It held altitude. This is something new.
 
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