SR22 Avionics

Guest Discussion
1

I learned some things about the SR22’s avionics that I thought other owners might find interesting. A lot of this is small detail that might be fairly dull to non-gearheads. Also, some of this information was in previous posts. I welcome corrections to the many details below.

  1. There is no way to download a flight plan or waypoints or anything else from a laptop PC to the GNS 430’s. This is unlike Garmin’s portables, which may be downloaded. I think the reason for this restriction is that Garmin is worried about the liability in case there is a mismatch between the database used to create a flight plan on the PC and the GNS 430.

  2. The GNS 430’s have an “Aviation Output” RS-232 channel, which tranmits “PVT”, position, velocity, and time once a second. This goes to the Arnav display, but could also be tapped into by other things, perhaps through a cabin-accessible RS-232 connector. I plan to have this output channel wired to a DB-9 in the cabin so that I can have it drive Jeppesen IFR FliteStar running on a laptop. The value in doing this is that

a. It will keep tracks, like the handheld’s’, unlike the GNS 430’s.

b. Poor man’s EGPWS.

c. Makes flight replanning from present position easier.

The cost of adding this connector should be insignificant.

  1. There are four bidirection RS-232 ports and two pairs of ARINC 429 inputs/outputs on each GNS 430.

  2. Channel # 1’s input is connected to the transponder, so that the GNS 430 gets pressure altitude.

  3. Channel #1’s output is the “aviation output”, which goes to the Arnav ICDS 2000.

  4. Channel #2 is unused, but is reserved for Ryan TCAD (or presumably other TCAS/TCAD units as well).

  5. Channel #3 is connected to the other GNS 430, for cross-fill.

  6. Channel #4 is for the Stormscope, except that in the SR22 the Stormscope is only connected to the Arnav and the Sandel (two displays is enough for me).

  7. The ARINC 429 output #1 goes to the autopilot and the Sandel’s GPS input.

  8. The ARINC 429 output #2 goes to the Sandel’s VOR input.

  9. The ARINC 429 input #1 comes from the Sandel’s selected course bearing output.

  10. The ARINC 429 input #2 is unused.

  11. I think the second GPS’s assignments are similar (transponder goes to both units), except that it is connected to the second CDI head instead of the Sandel and uses (I think) a combination of the ARCINC 429 I/O and the analog signals.

  12. Cirrus has been experimenting with a unit by Honeywell that combines EGPWS (Enhanced Ground Proximity Warning System) and TCAS I. Flight tests show the EGPWS to be quite accurate. Honeywell is entering the GA market with a repackaged version of what they sell for the biz jet market. They claim that their EGPWS terrain database is better than anyone’s and it accurately displayed (on what display, I don’t know) the hills around Duluth.

  13. Cirrus has been looking at the Shadin ADC-200 air/data/fuel computer as a possible factory option. The fuel flow sensor in the SR22 is already a Shadin unit, which makes the Shadin air/data/fuel unit easier to add. This will communicate with one of the GNS 430’s through one of the unused RS-232 ports.

  14. The SR20 that J & R Avionics of Hayward CA added a Ryan TCAD to is still down (after 6-8 months), waiting for FAA STC or Form 337 approval (not sure which). The problem is that they mounted an externa antenna and needed Cirrus or a DER (Designated Engineering Representative) to sign off on the mechanical integrity of the a/c after this antenna was mounted. Cirrus didn’t help as their engineers were busy with Cirrus’s agenda and it took a long time for J & R to realize this, find a DER (in Oregon, btw), get him to do the work, etc. This is a cautionary tale. I certainly don’t want my a/c down for a long time, so I won’t be adding anything with an external antenna unless I’m sure that it will be approved. J & R is hoping that all the approvals will be done soon.

  15. If the antenna problem can be solved, the Ryan unit with active interrogation, the 9900BX, still is not STC’s which means that you have to settle for the 9900B for now. Ryan is hoping for the STC “any month now”. The “B” can be upgraded to the “BX” for about $6,000, which is the difference in the price for the “B” and the “BX” models new. Just a circuit board swap to upgrade.

  16. Due to the lack of the STC on the Ryan active unit, Cirrus is more actively looking at the BF Goodrich Skywatch (and the Honeywell unit).

  17. The Trimble TRA3000 Radar Altimeter’s antenna must be mounted outside the skin, as even the non-lightning-protected skin of the SR22 reflects the 4 GHz signal too much. So the RA has the same problem as the Ryan TCAD – if you mount the antenna your a/c may be grounded for months.

The Honeywell unit, once blessed by Cirrus, sounds like a much better alternative than having a local shop add the Ryan TCAD and the Trimble RA. I plan to have the Arnav engine monitoring and the Shadin air/fuel/data computer added (no holes in the skin or the panel), along with Bose headset jacks and an RS-232 output from one of the GPS’s.

I pick up N567AB, SR22 #30, on 5/30. They had told me, just 2.5 weeks ago, that I could pick it up on 5/25, but I guess their production people are a little optimistic.

2

Robert,

Thanks for posting all of that useful info.

… along with Bose headset jacks and an RS-232 output from one of the GPS’s.

I’ve got some Bose headset jacks on order, but I’m still wavering on whether I’ll install them or not. I understand that the Bose jacks incorporate earphones, microphone, and power into a single connector. Very neat, very easy, and very incompatible with all other brands of headsets.

It would cost about $200 each to convert my existing headsets from a battery pack to panel power. Of course if you’re concerned about a measly $200 per headset, you shouldn’t be fooling around with Bose gear in the first place :slight_smile:

A bigger concern is the handheld radio I carry as a backup. I understand (although I haven’t tried it) that handhelds are almost worthless in the cockpit without a headset adapter. The Bose headsets with the panel power plug are incompatible with handheld headset adapters.

Another, lesser concern is not being able to use the headsets in any other airplane and not being able to use any other headset in my plane.

I’ll be in Duluth picking up SR22 #32 from June 1 through June 5. I hope I see you there.

-Mike

3

a. It will keep tracks, like the handheld’s’, unlike the GNS 430’s.

For what it’s worth, the ARNAV will display tracks if configured for north-up (and perhaps DTK-up, not sure) mode.

c. Makes flight replanning from present position easier.

This is one of my early Stupid GNS430 Tricks–set unit 1 to auto-crossfill to unit 2, but not the other way. You can then do all the what-if things on unit 2 without upsetting the autopilot, and when you’re done you can always hit ->D on unit 1 and unit 2 will fall slavishly in line with it.

  1. The Trimble TRA3000 Radar Altimeter’s antenna must be mounted outside the skin, as even the non-lightning-protected skin of the SR22 reflects the 4 GHz signal too much. So the RA has the same problem as the Ryan TCAD – if you mount the antenna your a/c may be grounded for months.

I think RA’s are probably the swirls on top of the icing on top of the cake. You need 'em if you plan on getting a Cat II ILS waiver, but they make pretty lousy ground prox alarms (since they look down, rather than forward) and if you get EGPWS in some other form, it becomes a pretty expensive bungee-cord-with-belt-and-suspenders for a low ILS approach.

I pick up N567AB, SR22 #30, on 5/30. They had told me, just 2.5 weeks ago, that I could pick it up on 5/25, but I guess their production people are a little optimistic.

They’ve got a lot of glare shields to replace…

An excellent geek-o-rama writeup, thanks.

4

…as even the non-lightning-protected skin of the SR22 reflects the 4 GHz signal too much

Are you saying the skin of the SR22 isn’t lighting protected? I know in the Diamond DA40, they included a layer of copper-mesh when they lay down the layers of the fuselage, to provide lighting protection. They don’t do that in the non-IFR DA20, and the factory guys said it would explode if it took a lightning hit. I didn’t see this mentioned in the SR22 POH, but I thought it was an IFR certification requirement.

-Curt

5

“The GNS 430’s have an “Aviation Output” RS-232 channel, which tranmits “PVT”, position, velocity, and time once a second. This goes to the Arnav display, but could also be tapped into by other things, perhaps through a cabin-accessible RS-232 connector. I plan to have this output channel wired to a DB-9 in the cabin so that I can have it drive Jeppesen IFR FliteStar running on a laptop.”

Keep us posted on how this works. I have planned on using a laptop with the Jeppesen FlightStar and FlightMap running, but drive it with a handheld GPS. Using the 430’s output should simplify the setup. Keep us posted on how this works.

“Channel #4 is for the Stormscope, except that in the SR22 the Stormscope is only connected to the Arnav and the Sandel (two displays is enough for me).”

I thought, per another post, that the Stormscope only drove the Arnav, not the Sandel. It is good to learn that at least the Sandel is receiving Stormscope data. Is there a reason that the Stormscope input for the 430 is not used? I would think that in bad weather you would want the #2 Garmin 430 to be able to show the “weather” page with Stormscope data.

“Cirrus has been looking at the Shadin ADC-200 air/data/fuel computer as a possible factory option. The fuel flow sensor in the SR22 is already a Shadin unit, which makes the Shadin air/data/fuel unit easier to add. This will communicate with one of the GNS 430’s through one of the unused RS-232 ports.”

This is good news. Keep us posted on what you learn on this. Would the computer unit for this mount in the tailcone area along with the gyro for the Sandel? If so, Cirrus would have to bring the pitot and static lines back to this area.

"If the antenna problem can be solved, the Ryan unit with active interrogation, the 9900BX, still is not STC’s which means that you have to settle for the 9900B for now. Ryan is hoping for the STC “any month now”. The “B” can be upgraded to the “BX” for about $6,000, which is the difference in the price for the “B” and the “BX” models new. Just a circuit board swap to upgrade.

Due to the lack of the STC on the Ryan active unit, Cirrus is more actively looking at the BF Goodrich Skywatch (and the Honeywell unit)."

Hopefully Cirrus will offer one or the other of these units as a factory option. Keep us posted on this.

"The Trimble TRA3000 Radar Altimeter’s antenna must be mounted outside the skin, as even the non-lightning-protected skin of the SR22 reflects the 4 GHz signal too much. So the RA has the same problem as the Ryan TCAD – if you mount the antenna your a/c may be grounded for months.

The Honeywell unit, once blessed by Cirrus, sounds like a much better alternative than having a local shop add the Ryan TCAD and the Trimble RA."

Agree! Question: If you could mount the TRA3000, where would you put the display?

“I plan to have the Arnav engine monitoring and the Shadin air/fuel/data computer added (no holes in the skin or the panel), along with Bose headset jacks and an RS-232 output from one of the GPS’s.”

Is Cirrus doing the Shadin install? Do you have any figures on the cost?

Per a prior post, I thought Cirrus was installing the Bose connectors at no charge. Are they charging for this? Do you know the figure?

Are you getting a BNC connector installed for the handheld com? In response to the question regarding use of the Bose connector, making the adaptor from the Bose connector to the handheld should not be too difficult. The Bose will operate normally (without noise reduction) in the absense of ANR power, so you should be able to construct an adapter for the mike and headset lines to the handheld.

What I plan to do is get the Bose with the conventional aircraft plugs and then when my SR22 comes up (Jan. 2002!) get the panel cord from Bose.

Robert: Thanks for your complete and informative post. I think I will just tell Cirrus “I want the Robert Bedichek special” on my SR22! Keep us posted on the evolving items as well as the use of the laptop with the Garmin output.

6

There is conductive mesh under some parts of the SR20 and SR22’s skin, but not everywhere. There is a 6" wide strip of mesh that runs from the firewall back the length of the plane, along the centerline of the belly. There are other parts with mesh, but I don’t know where they are. I do know that they left a mesh-free area in one place so that they could mount one of the GPS antennas inside the plane. I guess the 1GHz of the GPS signal goes through the non-mesh part.

…as even the non-lightning-protected skin of the SR22 reflects the 4 GHz signal too much

Are you saying the skin of the SR22 isn’t lighting protected? I know in the Diamond DA40, they included a layer of copper-mesh when they lay down the layers of the fuselage, to provide lighting protection. They don’t do that in the non-IFR DA20, and the factory guys said it would explode if it took a lightning hit. I didn’t see this mentioned in the SR22 POH, but I thought it was an IFR certification requirement.

-Curt

7

My comments preceed the parts of your post to which I am responding.
According to two people at Cirrus, the WX500 drives the Sandel HSI and the Arnav display. The POH in places says that the Sandel is driven and in other places implies that it is just the Arnav which is connected to the WX500. Those later reference are probably hold-overs from the SR20 POH (i.e., before the Sandel).
I don’t know why it is not also connected to the 430 – perhaps it was in anticipation of all the RS-232 ports being used for other things. Perhaps they felt that it was superflous.

I thought, per another post, that the Stormscope only drove the Arnav, not the Sandel. It is good to learn that at least the Sandel is receiving Stormscope data. Is there a reason that the Stormscope input for the 430 is not used? I would think that in bad weather you would want the #2 Garmin 430 to be able to show the “weather” page with Stormscope data.
See http://www.shadin.comShadin’s web site for more information on the ADC-200. They list it for between $3,100 and $3,600 depending on which fuel-flow sensor is used. I don’t know where it will be mounted.
“Cirrus has been looking at the Shadin ADC-200 air/data/fuel computer as a possible factory option. The fuel flow sensor in the SR22 is already a Shadin unit, which makes the Shadin air/data/fuel unit easier to add. This will communicate with one of the GNS 430’s through one of the unused RS-232 ports.”

This is good news. Keep us posted on what you learn on this. Would the computer unit for this mount in the tailcone area along with the gyro for the Sandel? If so, Cirrus would have to bring the pitot and static lines back to this area.

"If the antenna problem can be solved, the Ryan unit with active interrogation, the 9900BX, still is not STC’s which means that you have to settle for the 9900B for now. Ryan is hoping for the STC “any month now”. The “B” can be upgraded to the “BX” for about $6,000, which is the difference in the price for the “B” and the “BX” models new. Just a circuit board swap to upgrade.

Due to the lack of the STC on the Ryan active unit, Cirrus is more actively looking at the BF Goodrich Skywatch (and the Honeywell unit)."

Hopefully Cirrus will offer one or the other of these units as a factory option. Keep us posted on this.

"The Trimble TRA3000 Radar Altimeter’s antenna must be mounted outside the skin, as even the non-lightning-protected skin of the SR22 reflects the 4 GHz signal too much. So the RA has the same problem as the Ryan TCAD – if you mount the antenna your a/c may be grounded for months.

The Honeywell unit, once blessed by Cirrus, sounds like a much better alternative than having a local shop add the Ryan TCAD and the Trimble RA."
The only possible place that I know of for the TRA3000’s display (the TRI40) is where the fuel-flow-during-climb placard is, above the engine instruments. Or the bolster, but I don’t want to do this. But it is all moot until someone is able to mount an external antenna without Cirrus’s help and still get FAA approval.

Agree! Question: If you could mount the TRA3000, where would you put the display?

“I plan to have the Arnav engine monitoring and the Shadin air/fuel/data computer added (no holes in the skin or the panel), along with Bose headset jacks and an RS-232 output from one of the GPS’s.”

No, it will be Top Gun Aviation in Stockton, CA, the closest Cirrus service center to me. They may use J & R Avionics of Hayward for the more technical parts.

Is Cirrus doing the Shadin install? Do you have any figures on the cost?

I didn’t know about this.

Per a prior post, I thought Cirrus was installing the Bose connectors at no charge. Are they charging for this? Do you know the figure?

This would require an external antenna, or an antenna switch, both of which are problematic. I plan to trust the 430’s and the Sr22’s electrical system.

Are you getting a BNC connector installed for the handheld com? In response to the question regarding use of the Bose connector, making the adaptor from the Bose connector to the handheld should not be too difficult. The Bose will operate normally (without noise reduction) in the absense of ANR power, so you should be able to construct an adapter for the mike and headset lines to the handheld.

Sounds like a good plan.

What I plan to do is get the Bose with the conventional aircraft plugs and then when my SR22 comes up (Jan. 2002!) get the panel cord from Bose.

I’m glad it was helpful.

Robert: Thanks for your complete and informative post. I think I will just tell Cirrus “I want the Robert Bedichek special” on my SR22! Keep us posted on the evolving items as well as the use of the laptop with the Garmin output.