If I have two AHRS can I get rid of my vacuum system?

[jlunseth]

Wow. I am going to have to rethink my panel rebuild plan. I was going to put a backup alternator in the aircraft, which would require removing the vacuum. That would give me a backup to drive a dual GI275 install. But if both 275's go out, there would be no AI at all, and not even an HSI as a backup indicator for bank. I guess I would be stuck with the compass and the GTN750 for bank. That would be really ugly. And here I was worrying about the backup batteries not being of long enough duration in the 275s. Very much appreciate the information. For future reference, Garmin has a Pilot Help number, 1-866-739-5687, I have used it a couple of times on minor issues, they are very responsive.

[PT20J]

Interesting that they both do exactly the same thing. Do each of the GI 275s have internal ADAHRS or is the lower one receiving ADAHRS info from the top one? It will be interesting to see what Garmin has to say.

Skip

[RobertGary1]

8 minutes ago, PT20J said:

Interesting that they both do exactly the same thing. Do each of the GI 275s have internal ADAHRS or is the lower one receiving ADAHRS info from the top one? It will be interesting to see what Garmin has to say.

Skip

They both have their own. 

[EricJ]

My vacuum AI is only there to feed my chronically inop Century III autopilot, which I'm about to give up on, again.    I'd probably replace the vacuum AI with a 2nd G5 with an external antenna.   Two G5s back each other up nicely.  

I had been looking strongly at a Dynon glass panel or similar, but last month I had an alternator failure and flew home with everything turned off.   I was glad I had the air instruments, so that's kinda influenced my plans.

 

[jlunseth]

12 minutes ago, EricJ said:

I had been looking strongly at a Dynon glass panel or similar, but last month I had an alternator failure and flew home with everything turned off.   I was glad I had the air instruments, so that's kinda influenced my plans.

Yup, that's the problem in the models with one alternator. And if the whole electronic gauge system is subject to failure independent of the alternator, well, what do you really have? 

[Yetti]

3 hours ago, jlunseth said:

Yup, that's the problem in the models with one alternator. And if the whole electronic gauge system is subject to failure independent of the alternator, well, what do you really have? 

The Dynon has a battery for the primary display.  Will last up to 1 hour when new.  Has a battery test to tell when to replace.   The Backup instrument a D10A has it's own battery.   In theory you could have a jump batter that plugs into the cigarette lighter plug that would get you another hour.  Say an SLA 17Ah battery

[Ragsf15e]

22 minutes ago, Yetti said:

The Dynon has a battery for the primary display.  Will last up to 1 hour when new.  Has a battery test to tell when to replace.   The Backup instrument a D10A has it's own battery.   In theory you could have a jump batter that plugs into the cigarette lighter plug that would get you another hour.  Say an SLA 17Ah battery

Any idea what requirements their ahrs has for aiding?

[PT20J]

@RobertGary1Have you heard anything further from Garmin? It’s been a week. I emailed Garmin support and asked several detailed questions about the G5’s use of GPS and air data and its failure modes several days ago and haven’t heard anything. I’m concerned because my plan is to install a G3X Touch backed up with a G5.

You might consider filing a Service Difficulty Report to alert others — I think this certainly warrants it.

https://www.faa.gov/forms/index.cfm/go/document.information/documentID/184424

[Yetti]

3 hours ago, Ragsf15e said:

Any idea what requirements their ahrs has for aiding?

The screen and the Ahrs would be powered by the back up battery.   The breaker  for both the 10 inch and 7 inch screen is 5 amps one for each screen.   If you have two screens you could have two back up batteries.  So you could run one screen for an hour.  Then the other screen for an hour.  Then the D10A for an hour.  on their separate battery  Given managing everything properly.

 

Edited May 27, 2021 by Yetti

[David Lloyd]

A few years ago I was flying the RV with two Dynon 7" screens to Pittsburgh.  About 40 miles south of AGC, the alternator quit.  AGC was IFR, nothing but good VFR weather and forecast behind me.  Did a little figuring and told ATC I was returning home,  alternator out.  Turned off 1 screen and the strobe. SL30 and one Dynon, with the EMS, transponder, ADSB stayed on.  I think the amp draw was 5-6.  Landed at home about an hour and a half later, still showing 11.5 volts on the main battery.  I think the SL30 and transponder both would work down to about 9 volts.  Don't remember but the Dynon might switch to the backup battery at 10 volts.  It is always best if you know and understand what your plane can do.

[PT20J]

On some thread I said I thought the FAA requirement for backup batteries was one hour. I looked it up and its one hour for airplanes certificated to fly above 25,000 ft and half an hour for those certificated to fly below that altitude. It seems that manufacturers are designing to meet the 1 hour requirement. 

Skip

[Ragsf15e]

47 minutes ago, Yetti said:

The screen and the Ahrs would be powered by the back up battery.   The breaker  for both the 10 inch and 7 inch screen is 5 amps.   If you have two screens you could have two back up batteries.  So you could run one screen for an hour.  Then the other screen for an hour.  Then the D10A for an hour.  on their separate battery  Given managing everything properly.

 

I guess I was think about the required aiding for their attitude source - internal gps, panel gps, pitot, no aiding?  I.e. do they require gps or pitot input like G5s?

[PT20J]

Just now, Ragsf15e said:

I guess I was think about the required aiding for their attitude source - internal gps, panel gps, pitot, no aiding?  I.e. do they require gps or pitot input like G5s?

It’s kind of hard to figure this stuff out from the meager details the manufacturers provide. 

[Yetti]

48 minutes ago, Ragsf15e said:

I guess I was think about the required aiding for their attitude source - internal gps, panel gps, pitot, no aiding?  I.e. do they require gps or pitot input like G5s?

There is the screen, there is a magnetometer box there is a VFR GPS antenna, and an AHRS box that has pitot and static line inputs (and one more input for AoA).  All of these are powered through the network cables. So that is your 5 amps.  With this you get Synthetic Vision and compass Navigation with VFR map.

 

IFR Panel GPS is done from a certified WAAS IFR box so that is another circuit.

If you had Autopilot Servos those are powered through another 15 Amp Circuit. 

Depend on where you are and how you need to get down, I could see pulling all the Dynon CBs and leaving the ship  power for the IFR GPS and the Autopilot servos and flying that way.

And shutting down extra Dynon Screen.

You still have the standby Dynon D10A which has Attitude and compass along with Airspeed and altitude.   It has a Pitot port and a static port.   Do you shut it down till you need it and then bring it back online when the other batteries go?

There is a self test that is done on the main screen batteries every 6 months.    When you shut the plane off and select it will run the screen down to a certain voltage and time it.   If the battery won't support 45 minutes of run time it will tell you to replace it.   It charges the battery next time you fire up the plane/panel

 

[Fly_M20R]

8 hours ago, jlunseth said:

Wow. I am going to have to rethink my panel rebuild plan. I was going to put a backup alternator in the aircraft, which would require removing the vacuum. That would give me a backup to drive a dual GI275 install. But if both 275's go out, there would be no AI at all, and not even an HSI as a backup indicator for bank. I guess I would be stuck with the compass and the GTN750 for bank. That would be really ugly. And here I was worrying about the backup batteries not being of long enough duration in the 275s. Very much appreciate the information. For future reference, Garmin has a Pilot Help number, 1-866-739-5687, I have used it a couple of times on minor issues, they are very responsive.

If you have a Flightstream 210 to allow for ADS-B traffic and Wx to be sent to your iPad (Garmin Pilot or Foreflight) and also sync flight plans then it has a built-in AHRS which can be displayed on the Sythetic Vision page of Garmin Pilot (not sure about Foreflight). Great backup AI as long as you have avionics master on. The Flightstream 510 will also send Attitude info to the iPad "from a compatible flight deck or display".

CK

[Ragsf15e]

14 minutes ago, Fly_M20R said:

If you have a Flightstream 210 to allow for ADS-B traffic and Wx to be sent to your iPad (Garmin Pilot or Foreflight) and also sync flight plans then it has a built-in AHRS which can be displayed on the Sythetic Vision page of Garmin Pilot (not sure about Foreflight). Great backup AI as long as you have avionics master on. The Flightstream 510 will also send Attitude info to the iPad "from a compatible flight deck or display".

CK

Yeah it’s awesome that many new devices have backup attitude info like that.  FLight Stream, GTX345, etc.  unfortunately, it turns out they may all be reliant on the same power as the G5s or GI275s.  

[Yetti]

54 minutes ago, Ragsf15e said:

Yeah it’s awesome that many new devices have backup attitude info like that.  FLight Stream, GTX345, etc.  unfortunately, it turns out they may all be reliant on the same power as the G5s or GI275s.  

The stratux with a ahrs module will also send data to a tablet.   So seperate but redundant both in power source and ahrs

[PT20J]

58 minutes ago, Ragsf15e said:

Yeah it’s awesome that many new devices have backup attitude info like that.  FLight Stream, GTX345, etc.  unfortunately, it turns out they may all be reliant on the same power as the G5s or GI275s.  

Well…… I installed a GTX 345 connected to my GNS 430W. It Bluetooths ADS-B Out and AHRS to my iPad running Foreflight. Traffic and weather work great. One VMC day I tried flying the Foreflight attitude indicator beamed from the 345. Couldn’t control the airplane. Called Garmin and they said AHRS in 345 is same as other Garmin products - try Garmin Pilot. I did. Same E-ticket ride. My Avionics shop had the 345 replaced on warranty and told me that Garmin had been quietly replacing a lot of GTX 345s with bad AHRS. I personally leveled the airplane and calibrated the AHRS per Garmin’s procedure after replacement. The new one works  BUT….. you have to calibrate Foreflight to 0 pitch and 0 bank. It works fine for that flight. But every new flight seems to require recalibration. Bottom line: I thought this would be a good emergency backup, but I don’t trust it.

Skip

[Fly_M20R]

13 minutes ago, Yetti said:

The stratux with a ahrs module will also send data to a tablet.   So seperate but redundant both in power source and ahrs

True! 

[EricJ]

15 minutes ago, Yetti said:

The stratux with a ahrs module will also send data to a tablet.   So seperate but redundant both in power source and ahrs

I've not been able to get that to work in any kind of reliable fashion.    I used to think of that as a backup until I tried it and found it unreliable.   I don't know where the problem lies, if it is in the EFB or where it is.

 

 

[PT20J]

1 minute ago, EricJ said:

I've not been able to get that to work in any kind of reliable fashion.    I used to think of that as a backup until I tried it and found it unreliable.   I don't know where the problem lies, if it is in the EFB or where it is.

 

 

I see a market for a box you place on the glareshield that has a miniature, battery-operated vacuum pump and vacuum attitude gyro 

[Yetti]

9 minutes ago, EricJ said:

I've not been able to get that to work in any kind of reliable fashion.    I used to think of that as a backup until I tried it and found it unreliable.   I don't know where the problem lies, if it is in the EFB or where it is.

 

 

Given that would be third or 5th back up I doubt it would come into play.  You can install 2 AHRS boxes in the Dynon.  So one can fail over.

[Yetti]

And this is why not just anyone should design systems.   Prior to AWS second outage we were laughing about 3 servers and 2 availability zones on the east and one on the west coast.   Then it happened.   We only lost one server but the site stayed up.   So that said is when I read about chaos monkeys and designing to fail.   https://netflixtechblog.com/5-lessons-weve-learned-using-aws-1f2a28588e4c

[Ragsf15e]

3 hours ago, PT20J said:

Well…… I installed a GTX 345 connected to my GNS 430W. It Bluetooths ADS-B Out and AHRS to my iPad running Foreflight. Traffic and weather work great. One VMC day I tried flying the Foreflight attitude indicator beamed from the 345. Couldn’t control the airplane. Called Garmin and they said AHRS in 345 is same as other Garmin products - try Garmin Pilot. I did. Same E-ticket ride. My Avionics shop had the 345 replaced on warranty and told me that Garmin had been quietly replacing a lot of GTX 345s with bad AHRS. I personally leveled the airplane and calibrated the AHRS per Garmin’s procedure after replacement. The new one works  BUT….. you have to calibrate Foreflight to 0 pitch and 0 bank. It works fine for that flight. But every new flight seems to require recalibration. Bottom line: I thought this would be a good emergency backup, but I don’t trust it.

Skip

My GTX345 ahrs works reasonably well with my ipad.  The iPad is very old  though and either the iPad or BT link makes it a bit choppy and not fun to fly off of.

I use to consider it a backup for my vacuum adi, but now, anything that takes out my G5s is gonna kill the GTX345 too, so it’s useless.  Yetti’s Stratus with iPad is good, or dynon pocket panel.

Edited May 28, 2021 by Ragsf15e

[jlunseth]

Portable device like the Stratus or Stratux are worthless as a source for attitude data when your life is on the line. The data depends on the source device being fixed in place and not moving at all. Can’t be on a suction cup on the window, laying on the dashboard, sitting on the floor under a seat, etc. If it falls, gets kicked, touched, turbulence puts it somewhere else, you die. So yeah, if you want to bolt it to the frame in a way it can’t even turn on the bolt, that might be better than nothing, but you had better safetie the nut.