TruTrak Vision 385 Operation

[uk_figs]

Looking for guidance from people with Vizion autopilot experience. I was shooting approaches yesterday and on a couple of occasions the TruTrak did not behave as I expected, wondering if it is a procedural, system limitation, or other issue.
First incident was approach selected, crossing the IAF at the correct (designated on the chart) altitude in GPSS mode and altitude hold and the autopilot did not arm. The HSI glide slope indication was that I was above the glide slope.
Second incident was approach selected, crossing the IAF the autopilot armed however I manually selected the FAF crossing altitude and a 500ft rate of decent and the autopilot stayed in GPSS mode but appeared to lose the V Nav coupling and never coupled. Did I disconnect the V Nav mode by manually selecting the next altitude?

Last question has been discussed at length but what is the parameter to adjust that can somewhat reduce the porpoising in the turns in a hold.
Configuration is the Vizion is connected to a GNX375 via arinc 429 and I do not have the pitch autotrim module.
Appreciate any feedback.
Figs

 

[rleffler]

Looking for guidance from people with Vizion autopilot experience. I was shooting approaches yesterday and on a couple of occasions the TruTrak did not behave as I expected, wondering if it is a procedural, system limitation, or other issue.
First incident was approach selected, crossing the IAF at the correct (designated on the chart) altitude in GPSS mode and altitude hold and the autopilot did not arm. The HSI glide slope indication was that I was above the glide slope.
Second incident was approach selected, crossing the IAF the autopilot armed however I manually selected the FAF crossing altitude and a 500ft rate of decent and the autopilot stayed in GPSS mode but appeared to lose the V Nav coupling and never coupled. Did I disconnect the V Nav mode by manually selecting the next altitude?

Last question has been discussed at length but what is the parameter to adjust that can somewhat reduce the porpoising in the turns in a hold.
Configuration is the Vizion is connected to a GNX375 via arinc 429 and I do not have the pitch autotrim module.
Appreciate any feedback.
Figs

First incident - You need to intercept the glideslope from underneath.

second incident - I don’t know the answer, I never used that feature, except when my efis was controlling the altitude.

Last question - the Trutrak manual walks you through the process. There is a gain and sensitivity parameter for both roll and pitch. AFS used to have a better written procedure in their manuals. I don’t know if it’s still there or not. I uninstalled my Trutrak gear and switched to Dynon servos.

if you are using it conjunction with an efis, there may be a secondary, but similar procedure to configure these parameters on the efis.

 

[Tankerpilot75]

Figs,
Three things.
1. When flying an ILS/VDP approach make sure you have the appropriate navigation guidance selected on the gps and programmed in your EFIS.
2. Select “execute” after you’ve been “cleared for the approach” for a precision approach.
3. When flying an RNAV approach (LVP or VOR) you have to manually enter the step down altitudes in your EFIS PFD.

At least that how it works with my GRT EX system coupled to my Vizion 385. Jerry Morris has an old GRT HXr video with TruTrac autopilot going over his procedures flying the approach. You might find it useful.