Autopilot FAQ

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What is required for me to add the Dynon AP to my existing EFIS-D10A, EFIS-D100, or FlightDEK-D180?

1. Install pitch and/or roll servos to your aircraft.

2. Optionally, add the AP74 Autopilot Interface Module to your panel.

3. Upgrade your EFIS-D10A, EFIS-D100, or FlightDEK-D180 to version 5.0 firmware (or later)

4. Perform on-ground autopilot calibration

5. Perform in-air autopilot tuning

No hardware or other modification (other than firmware upgrade) for your EFIS-D10A, EFIS-D100, or FlightDEK-D180 is required.

Does the AP work with my EFIS-D10?

The EFIS-D10 is not compatible with the Dynon AP. An EFIS-D10 can be upgraded to an EFIS-D10A (which is compatible with the Dynon AP). Contact Dynon Technical Support for details.

If I install a Dynon AP (servos) and later upgrade to Dynon's Next Generation System, will I have to install different servos and wiring?

Dynon's servos are designed to work with both Dynon's current products and Dynon's Next Generation System. If you want to "future proof" your servo installation, run the Blue/White and Green/White wires along with the Blue and Green (DSAB) wires up to the panel. The Blue/White and Green/White wires are will be used in a new Next-Gen-specific redundant communication bus.

The AP74 will not be compatible with the Next Generation System.

What is the AP74 and is it required for the Dynon AP to work?

The AP74 is an optional, dedicated control and indicator panel for the Dynon AP. It's available in horizontal or vertical configuration. Primarily, the AP74 makes the AP more convenient and easier to use.

There are a few feature additions with the AP74:

  • You can pre-select which mode will be active when you engage the AP. So you can hit "NAV" before you hit "engage" and it will come on in NAV mode.
  • Voice alerts capability (not just for AP, but also for other alerts).
  • Auto-dimming (it has a light sensor that can use to automatically dim all Dynon instruments).
  • Bugs can be set with a knob instead of button pushes.

Is the HS34 functionality also included in the AP74?

Somewhat. Some of the front panel functionality - knobs and buttons, has been replaced (and improved upon) by the AP74. But the primary function of the HS34 - to allow you to connect your GPS and NAV radio to a Dynon EFIS for HSI and AP navigation sources, has not been replaced by the AP74.

Is the Dynon AP compatible with TruTrak's servos?

Electrically, no. Mechanically, yes. As TruTrak is the market leader, Dynon designed their servos to be mechanically similar for customers that would like to add a Dynon Autopilot to an aircraft that has previously had a TruTrak AP installed. Dynon's servos are cheaper, lighter, and smarter than competing servos.

Dynon offers servo installation kits for a number of aircraft, as well as a generic kit - see the Dynon Online Store for details.

Because our servos are mechanically similar to TruTrak's, we may be able to provide an autopilot solution for your airplane if there is a TruTrak servo configuration that is known to work in your type of aircraft. However, PLEASE DO NOT CALL TruTrak for advice on servo configuration if you intend to install a Dynon AP. DO seek out fellow builders of your aircraft type for this type of configuration information. Feel free to post questions to our forum and post results and relevant information to the Servo Application Guide.

What airplanes can the Dynon Autopilot be used in?

A list of aircraft that have been evaluated for the Dynon AP available on the Servo Application Guide.

In addition, your aircraft manufacturer (both Experimental and Light Sport Aircraft) may offer Dynon's instruments and AP as a factory option - contact them directly for details.

If your aircraft is not one that we currently support with an installation kit, and you'd be interested in working with Dynon to document your Dynon AP installation, see this post about becoming a beta tester.

What happened to the AP76 Advanced AP Module?

Originally announced to be available in late 2008, the official status of the AP76 is now "Project On Hold".

Dynon VP and COO Nick Bogner provided an explanation in a discussion thread on Dynon's Online Forum.

What happened to the SV52 Servo?

The SV32 (36 inch-pounds torque) and SV42 (55 inch-pounds of torque) in their various configurations such as long-arm and capstan seem to meet the vast majority of aircraft configurations. To date, there hasn't been demonstrated demand for the SV52's 72 inch-pounds of torque.

What is the current draw of the servos and AP74?

SV32 @ 12V

   Powered but disengaged: 0.1 amps
   Engaged and holding, 100% torque: 0.80 amps
   Engaged and moving, 100% torque: 1.33 amps

SV42 @12V

   Powered but disengaged: 0.1 amps
   Engaged and holding, 100% torque: 1.11 amps
   Engaged and moving, 100% torque: 2.03 amps


   Approx. 200mA at 12V

I'm building an RV and planning on using the new Dynon AP. Are both servos to be mounted in the fuselage or is the roll servo wing mounted?

Dynon's servo installation kits for the RV-7/8/9 are designed for mounting the roll servo in the right wing. If you wish to put it somewhere else, it will work, but Dynon's kits aren't designed for mounting the roll servo in other locations.

Dynon's RV-6 servo installation kit mounts the roll servo under the seat.

DSAB (Dynon Smart Avionics Bus) Wiring Questions

Can DSAB wiring be spliced in a star type config or must they be daisy chained? Is there any need for terminating resistors etc.?

Any wiring configuration is acceptable as long as all DSAB devices are electrically connected. So, star configuration would work, as would daisy chain configuration. Perhaps the only consideration is which devices would get disconnected if a wire breaks in any particular place. There is no need for terminating resistors.

How noise immune is the DSAB bus? Does it operate on a differential like two wire RS485 or is it just RS232 with your custom protocol on top?

DSAB is very robust and noise-resistant. DSAB is based on RS485 (now called EIA-485) based bus, with Dynon's DSAB protocol running on top of it.

Will long parallel runs of DSAB wires alongside power wires for the servo going to tolerate the noise generated by the servo?

Parallel runs with power lines won't cause interference to DSAB.

Should the DSAB wires be shielded from the power wires?

DSAB wiring doesn't need to be shielded from power lines.

Should DSAB wiring be "twisted pair"? Should it be shielded?

Twisted pair and shielded cable provide a level of noise immunity, but is generally not required for DSAB wiring.

How is this additional (EFIS-to-servo) data flow on the DSAB bus going to affect the performance of interdisplay communications?

The DSAB protocol is very efficient - there's ample "bus time" for both, especially since DSAB was originally designed / specified to accommodate EFIS-to-servo communication.

I remember somewhere you mentioned that the servo will have an embedded processor, how will this thing handle lost data etc.? Will the servo processor have smarts to report errors, torque, etc. to the EFIS for display and use for features like trim sensing etc?

Yes, the servo has an embedded processor. It's smart about lost data and has bidirectional communications so both it and the EFIS know if anything is up. For instance, it tells you if the servo is slipping from being overridden or not having enough torque for the air loads.

Can we get some details on the user interface for the AP?

The AP user interface is thoroughly documented, including screen shots, in the Pilot's User Guides for the EFIS-D10A, EFIS-D100, and FlightDEK-D180. The Pilot's User Guides can be downloaded prior to purchase or installation of servos (and the accompanying firmware upgrade).

One question that has been created by a comment posted on another forum. What is Dynon's response to the fact that most people with APs and EFISes that use them in IMC have the ability to rely on the AP to help them in the event they lose the EFIS? Now with your system, the EFIS is the AP so if you lose it, your AP is also lost. Now I know that most people using a EFIS in IMC have dual EFIS's of which either could be configured to run the AP. How hard is it to do a DASB reconfig in the air and is it feasable to do this in the event of an AP controlling EFIS goes tipup while in IMC? Next question is that of the pitot data being lost. How much is this going to impact the EFIS's ability to control the AP?

There's a fairly detailed procedure in calibrating the AP functionality to a particular aircraft, including the calibration of the servos. That calibration is not transferrable, nor can it be duplicated, between two EFIS units.

We'd never suggest someone fly in IMC with only one EFIS, any brand. So you have two, right?

Think of it this way: One is your EFIS, one is your EFIS + AP. Lose the EFIS, you still have EFIS+AP. Lose the EFIS+AP, you still have EFIS. You basically have the same level of redundancy as you would have if you had alternatively configured with a single set of flight instruments backed up with an autopilot.

If you have a standalone AP and it dies, you have no AP. A Dynon equipped plane would be no different. Loss of one device in the plane can mean loss of AP, but that's true in any install.

We aren't able to answer the loss of pitot question yet, as that portion of the AP is still in development. We are aiming for a system that will still control the plane just fine with no pitot, but this is not a promise yet.

Remember though, loss of pitot can be a problem with any AP, since it may try and hold airspeed to prevent a stall. Of course, as airspeed bleeds off, it will keep pointing the nose down trying to get more airspeed. It's a tradeoff between stall prevention and pitot loss.

Does the Dynon AP include Autotrim or Trim Sensing?

Trim control isn't currently a feature of the D10/D100 series. However, SkyView supports trim force sensing, and if you have the SV-AP-PANEL, auto-trim as well.

Does the Dynon AP include Altitude Hold?

Altitude Hold is an available feature if a pitch servo is installed, including the ability to both hold and change altitude.

My TruTrak AP features Altitude Hold and Ascend/Descend Rate. Will the Dynon AP do the same?

Better! The Dynon AP will fly to an actual altitude you dial in, not just vertical speed. So, you can dial in 8,500' even if you are currently at 4,850'. The Dynon AP will climb and descend to new altitudes at a rate you have set in the setup menu.

I have a Garmin GNS 480 and intended to hook up a TruTrak Digiflight II VSGV. This would have allowed me to have the 480 fly me through a precision approach, execute the missed approach, take me to the missed approach point and hold - all while providing both lateral and vertical steering from the 480 to the autopilot. I have not installed the AP yet. Will the Dynon AP provide the same functionality, including the vertical steering on the approach?

The Dynon AP does not currently have equivalent functionality to what is described.

One of APs I looked at has a reciprocal heading capability. Sort of "if suddenly in the gloop hit a button - AP takes you on a rate 1 turn around and brings you out of the IMC". Seemed like a good idea to me though never been (or plan to consciously get ) in a spot where I'd need it. Would it be hard to add that form of feature and if not would you?

The functionality as described is already a feature of the Dynon AP. There's a 180 turn button in the EFIS menu, and if you have the AP74, holding the engage button for two seconds does a 180.

In my aircraft and particular servo mounting, I need a slightly longer pushrod than the one supplied in the kit. Can I get custom pushrods from Dynon?

Dynon doesn't sell pushrods individually or in custom sizes outside of the kits. However, here are the specs:

  • 6063-T6 aluminum tubing (6061 would work fine, but the size we need for our rod ends is harder to source)
  • O.D. 0.375” (3/8”) fairly common. The 8 foot length costs around $6 from McMaster Carr.
  • I.D. can be anything LESS than .213” (a solid bar would be fine as well). The reasoning for the .213” is: A) minimum wall thickness for tubing strength. B) That happens to be the drill diameter required for a 1/4-28 tap.
  • Both ends need to be tapped for the spherical rod end bearings: we use 1/4-28 threads for ours. It could be whatever you need it to be for different rod end bearings though.
  • Drill the ends of each tube to .213” I.D. at a depth of 1” then tap.