Accutrak performance

[jmbaute]

We have the Brittain Accutrak in our 74 M20C. I have personally never witnessed this device to work when tracking a nav source, so I thought I'd throw out my observations and see what you guys think.

 

First:

I verified PC operation doing the taxi test. Works as expected.

In flight, I can command a roll using the accutrak knob. Works fine in either direction. Pretty rapid response.

 

What I can't figure out is if it is properly tracking the nav source. The CDI is hooked up to a G530. If I turn the unit off and let the plane go right of course, when I turn the autopilot back on it seems to try to pull me back. No noticeable response when I go left of course. No real difference between high/low sensitivity.

 

But, I just don't really know how this thing should behave. For example, how far off course will it let you go before it responds? One dot deflection? Two? 

 

The original owner of the plane insists it works...and in somewhat recent history the entire system was checked out by Brittain. So maybe it did work, but I'm not seeing it behave as I would expect. Granted, I've never owned a plane with an autopilot before. My first C model only had the regular PC.

 

Thoughts? Anyone have similar experience?

 

Thanks,

John

[Hank]

I have AccuTrak and AccuFlite, and can never remember which is which.

One follows the heading bug very well, and is sensitive to even tiny adjustments.

The other follows the 430 & CDI. It used to hunt a lot and not do much, then I had to start crabbing a lot with the heading bug, then that quit working. Turned out that the boot on one of my wing servos was torn. Remove the inspection panels just inboard of each aileron, watch closely with a flashlight while moving the aileron full up and down. It takes small hands to remove the single screw in the back of the servo; check attachment on the elevator servos in the radio compartment.

If needed, return to Brittain for fast, expensive repair. If it looks good, you can retape them while out. Brittain will tell you the exact orang to use to told the rubber boot on, fold it over and tape down with 3M electrical tape. Now both systems work pretty well.

Good luck. Let us know what you find.

[N601RX]

If it will manually roll the plane left and right most of it is working.  Try changing CDI sensitivity to 1 or .3 miles on the gps.  You will also want to keep the ailerons lubed and free so it can respond to small changes.  The manual knob you mentioned also has to be in the center for it to track a nav source.

[Hector]

If it will manually roll the plane left and right most of it is working. Try changing CDI sensitivity to 1 or .3 miles on the gps. You will also want to keep the ailerons lubed and free so it can respond to small changes. The manual knob you mentioned also has to be in the center for it to track a nav source.

+1. Mine would wonder off quite a bit before it would correct (wired to my GPS) and frankly I though I could hand fly much better and was rather disappointed about the performance. Then I read a post here and changed the CDI sensitivity to .3 miles full deflection. It made all the difference in the world!!

[StinkBug]

Mine seems to work very well on longer trips. When you first turn it on if you're not perfectly centered it will overcorrect, overshoot, then correct back, and it will take a while to stabilize. After about 10 minutes my track is almost perfectly straight. I dont seem to notice any difference between hi and lo though. This is all on GPS. If I hit the button to switch over to VLOC it's very responsive to the needle, but when tracking a VOR the needle also moves quite a bit more than the GPS. Where do I find this CDI sensitivity setting in a 430? I'd like to see what mine is set at.

[carusoam]

You might be witnessing the scalloped shape of VOR navigation lines compared to the perfectly straight magenta line...?

Best regards,

-a-

[N601RX]

Mine seems to work very well on longer trips. When you first turn it on if you're not perfectly centered it will overcorrect, overshoot, then correct back, and it will take a while to stabilize. After about 10 minutes my track is almost perfectly straight. I dont seem to notice any difference between hi and lo though. This is all on GPS. If I hit the button to switch over to VLOC it's very responsive to the needle, but when tracking a VOR the needle also moves quite a bit more than the GPS. Where do I find this CDI sensitivity setting in a 430? I'd like to see what mine is set at.

Approach mode will switch over automatically, but the older king units have a way to do it manually also. Check the garmin manual.

[StinkBug]

Approach mode will switch over automatically, but the older king units have a way to do it manually also. Check the garmin manual.

That only helps when you're actually close to the destination. I'm talking about making the AP track more accurately while enroute. I found my answer on the 430 simulator though. AUX page, 3rd box over in the CDI menu you can select the sensitivity .3, 1.0, 2.0, or Auto.

[cliffy]

THE ACCUTRAC MANUAL ALSO SAYS TO "BE ON COURSE" BEFORE YOU ENGAGE IT. sorry for the caps