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  #1  
Old 09-03-2018, 04:52 PM
pilotdds pilotdds is offline
 
Join Date: Nov 2005
Location: sck ca
Posts: 56
Default trio autopilot pitch issues

I have struggled for several years getting my trio ez pitch system to be usable.Does anyone have a picture or drawings of the pitch servo mount for a trio.It has been suggested thst there is flex in the servo mount causing oscillations and porpoising.FYI factory is very supportive.The roll system is flawless
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  #2  
Old 09-03-2018, 05:21 PM
Finley Atherton Finley Atherton is offline
 
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Location: AUSTRALIA
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This is my experience with the Trio and my RV 9A - don’t know if it is relevant to the RV 8.

Installed as per the plans my Trio pitch servo was over sensitive and prone to oscillations and porpoising. I solved the problems by moving the servo push rod higher up the elevator bellcrank to the point just below where the two halves of the bellcrank widen to accommodate the elevator push rod. This effectively “lowers” the gearing of the servo. You may be able to achieve a similar result by moving the push rod on the servo arm inwards. If you try this make sure you comply with the warnings in the manual about not allowing the servo arm to over center or limit the movement of the elevator.

Fin.

Last edited by Finley Atherton : 09-03-2018 at 05:24 PM.
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  #3  
Old 09-03-2018, 07:06 PM
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roadrunner20 roadrunner20 is offline
 
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Location: Bay Pines, FL (based @ KCLW)
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Since you said you've been having the issue for several years...
Not sure if you have this issue, but this happened to me.

I purchased a used EZHold3 a few years ago & upon engaging, I had extreme oscillations & propoising. I worked with Trio to correct the issue without success.

Apparently, I had pulled the installation instructions off their website & they had the static & pitot ports reversed. They've since corrected the doc. If you're looking at an old doc you may have downloaded, it may be incorrect.
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  #4  
Old 09-03-2018, 08:02 PM
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Sam Buchanan Sam Buchanan is offline
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Quote:
Originally Posted by pilotdds View Post
I have struggled for several years getting my trio ez pitch system to be usable.Does anyone have a picture or drawings of the pitch servo mount for a trio.It has been suggested thst there is flex in the servo mount causing oscillations and porpoising.FYI factory is very supportive.The roll system is flawless
The pitch servo should work as well as the roll servo. Don't know if this is applicable to your RV-8 but here are photos of the servo in my RV-6:



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  #5  
Old 09-03-2018, 09:40 PM
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DanH DanH is offline
 
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Location: 08A
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Quote:
Originally Posted by pilotdds View Post
I have struggled for several years getting my trio ez pitch system to be usable.Does anyone have a picture or drawings of the pitch servo mount for a trio.It has been suggested thst there is flex in the servo mount causing oscillations and porpoising.FYI factory is very supportive.The roll system is flawless
Does it look like this one? I designed it for them about 12 years ago, but I don't know if they subsequently distributed the drawings to RV-8 builders.

That's a stiffness check in the photo. The dial indicator said deflection was only 0.002" with the servo clutch at the slip point.



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Last edited by DanH : 09-05-2018 at 05:19 AM.
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Old 09-03-2018, 09:41 PM
PCHunt PCHunt is offline
 
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You haven't mentioned any attempt to change the gain settings in the software. The autopilot is very customizable using the various gain settings. Have you tried that?

I had to dial the gains down to get my Trio to work the way I wanted it to, especially for the pitch channel in turbulence.
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  #7  
Old 09-03-2018, 10:20 PM
pilotdds pilotdds is offline
 
Join Date: Nov 2005
Location: sck ca
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Default trio pitch issues

Yes I have reset the gain and deadband per the manual and Chucks instructions many times. The control units and the servos have been back to trio for testing and the pitot and static ports on the control unit have been verified and even vented to cabin pressure for one test.It did not seem to make a difference. Dan, Your mount looks very rigid how does the trio perform for you?I note your servo arm is mounted in the upright position .Thanks for the input.What was the thickness of the mount?
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Old 09-03-2018, 11:13 PM
BobTurner BobTurner is offline
 
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Location: Livermore, CA
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I have a Trio Pro in a -10, and it is rock-solid. If you want to fly over to LVK I can pull the aft bulkhead off and you can see how mine is mounted.
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  #9  
Old 09-04-2018, 03:56 AM
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DanH DanH is offline
 
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Quote:
Originally Posted by pilotdds View Post
Dan, Your mount looks very rigid how does the trio perform for you?I note your servo arm is mounted in the upright position .Thanks for the input.What was the thickness of the mount?
Flown it 800 hours now.

I can't locate the drawing on my hard drive.

No need to guess about mount stiffness; the check is easy. Set up a measurement device. Engage the servo. Pull the stick until the clutch slips. Read the measurement.
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  #10  
Old 09-04-2018, 05:17 AM
Tooch Tooch is offline
 
Join Date: Nov 2011
Location: Amelia, Va
Posts: 194
Default Pitch

I have had this problem since I put in the Pro Pilot about 4 years ago. Tried everything. Trio says my RV-7A may be out of CG but is is not. They said to try to put 30 pounds in the front passenger side near the rudder pedals just to see. I did and no difference. I checked my install of the servo and it is correct.

I'm used to it by now. Kinda get a slight rock up and down on a CC flight.
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