GI 275 install torture tests & performance without IAS & GPS

[Fly_M20R]

After loss of pitot input the IAS "red-x'd" on my dual GI 275 installation. I had the opportunity to test various failure considerations I had been thinking about to evaluate how the AHRS (attitude indicator) would perform. Would it "red-x", tumble or drift?

The failures were equivalent of having lost alternator and battery and therefore shutting down the panel as well as causing the pitot tube to freeze in IMC. Would the GI 275 AI survive?

Chris

 

 

[Utah20Gflyer]

Thanks!   I'm having a GI 275 HSI installed in my plane now and appreciate the work you did to flush out the capabilities of the 275.   Very thorough job!

[Fly_M20R]

10 hours ago, Utah20Gflyer said:

Thanks!   I'm having a GI 275 HSI installed in my plane now and appreciate the work you did to flush out the capabilities of the 275.   Very thorough job!

You will enjoy your new HSI!! 

The one request I made to Garmin re the HSI is that they also display groundspeed (GS) as one of the fields they have which is not being used at present. Should be a very easy update for them. 

 Have you thought about installing the VFR GPS option on it? Can turn out to be quite useful in case you lost the panel GPS.

Happy flying!!

Chris

[Utah20Gflyer]

11 hours ago, Fly_M20R said:

You will enjoy your new HSI!! 

The one request I made to Garmin re the HSI is that they also display groundspeed (GS) as one of the fields they have which is not being used at present. Should be a very easy update for them. 

 Have you thought about installing the VFR GPS option on it? Can turn out to be quite useful in case you lost the panel GPS.

Happy flying!!

Chris

A ground speed display would be nice, I hope they do something with that.

I hadn’t thought about a vfr gps as the only one available would be my I pad connected to a Sentry ADSB in device.  Not sure how that would interface.

I am having a Garmin 355 Waas gps/com installed as the primary navigation source and also tying in my Nav radio as well.  

[Mooney Dog]

1 hour ago, Utah20Gflyer said:

am having a Garmin 355 Waas gps/com installed as the primary navigation source and also tying in my Nav radio as well.  

I have the 375, and its great. All the GPS series from Garmin come with bluetooth connext, which is you have a source of ADSB in feeding to the device, should show it on your ipad as well if connected. If not they should link up the GPS location as well. 

[RobertGary1]

I tested that too unintentionally.

Never really came back  did for a bit but did slow roll of death until it went out again 

 

[RobertGary1]

14 hours ago, Fly_M20R said:

You will enjoy your new HSI!! 

The one request I made to Garmin re the HSI is that they also display groundspeed (GS) as one of the fields they have which is not being used at present. Should be a very easy update for them. 

 Have you thought about installing the VFR GPS option on it? Can turn out to be quite useful in case you lost the panel GPS.

Happy flying!!

Chris

In pfd and HSI backup install mode it doesn’t ever show the map view. 

[Fly_M20R]

8 hours ago, Utah20Gflyer said:

A ground speed display would be nice, I hope they do something with that.

I hadn’t thought about a vfr gps as the only one available would be my I pad connected to a Sentry ADSB in device.  Not sure how that would interface.

I am having a Garmin 355 Waas gps/com installed as the primary navigation source and also tying in my Nav radio as well.  

The VFR GPS is an option for the 275. It provides a glareshield mount antenna and is powered by the backup battery of the 275 in case of panel power failure that would disable your panel mounted waas gps. It will only come active once the 275 does not see the panel GPS anymore.

Chris

[Fly_M20R]

6 hours ago, RobertGary1 said:

I tested that too unintentionally.

Never really came back  did for a bit but did slow roll of death until it went out again 

 

Your failure is certainly quite unusual. Could it be that the airspeed was coming on and off quite abruptly because of the type of cover on your pitot tube? That may have thrown off the AHRS (????)

I believe Garmin is aware of your issue.

Chris

[Fly_M20R]

6 hours ago, RobertGary1 said:

In pfd and HSI backup install mode it doesn’t ever show the map view. 

Not sure what you mean by "HSI backup install"

[RobertGary1]

5 hours ago, Fly_M20R said:

Not sure what you mean by "HSI backup install"

Each 275 is installed in a set mode. If you set it as a back up the only pages accessible are pfd,hsi and map. The keys to do gps navigation etc are hidden.  
That is the required set up mode if you want it to monitor and switch on pfd failure. 

[RobertGary1]

5 hours ago, Fly_M20R said:

Your failure is certainly quite unusual. Could it be that the airspeed was coming on and off quite abruptly because of the type of cover on your pitot tube? That may have thrown off the AHRS (????)

I believe Garmin is aware of your issue.

Chris

I suspect it was because it was a very windy day and gps speed was a poor backup for airspeed for AHRS corrections. 
Garmin has returned the plane to me but never told me what they found. 

[Fly_M20R]

10 hours ago, RobertGary1 said:

Each 275 is installed in a set mode. If you set it as a back up the only pages accessible are pfd,hsi and map. The keys to do gps navigation etc are hidden.  
That is the required set up mode if you want it to monitor and switch on pfd failure. 

From what you are saying, your top unit is primary ADI (PFD) and bottom unit is HSI/Standby ADI. Since the bottom unit is HSI in normal ops it should show HSI and also have and HSI Map page, in addition to also having an ADI (PFD) page. As soon as you got a red-x the bottom should have automatically reverted to ADI and not allowed you to switch to any other page.

It sounds like that is what happened.

[Fly_M20R]

10 hours ago, RobertGary1 said:

I suspect it was because it was a very windy day and gps speed was a poor backup for airspeed for AHRS corrections. 
Garmin has returned the plane to me but never told me what they found. 

What was the groundspeed indicating on your GPS navigator? Was it fluctuating a lot while tracking a constant heading or only as you turned and the wind vector changed?

[RobertGary1]

3 minutes ago, Fly_M20R said:

From what you are saying, your top unit is primary ADI (PFD) and bottom unit is HSI/Standby ADI. Since the bottom unit is HSI in normal ops it should show HSI and also have and HSI Map page, in addition to also having an ADI (PFD) page. As soon as you got a red-x the bottom should have automatically reverted to ADI and not allowed you to switch to any other page.

It sounds like that is what happened.

Not sure what you are referring to but in the example set up you mention the vfr navigator is disabled in the 275. Only in the standalone mode can you enter waypoints etc in the 275. 

[Fly_M20R]

8 hours ago, RobertGary1 said:

Not sure what you are referring to but in the example set up you mention the vfr navigator is disabled in the 275. Only in the standalone mode can you enter waypoints etc in the 275. 

The VFR GPS in the bottom GI 275 (MFD/Standby ADI) is not enabled  as long the unit sees the panel mounted GPS which in my case is a 530W. The moment it does not see the panel mounted GPS it will become active and provide you with all GPS data (GS, TRK, GPS ALT, position) and allow you to go direct to a waypoint. The "direct" button is grayed out whenever it is inactive.

 

What did your groundspeed show on your panel mounted GPS navigator? 

[RobertGary1]

16 hours ago, Fly_M20R said:

The VFR GPS in the bottom GI 275 (MFD/Standby ADI) is not enabled  as long the unit sees the panel mounted GPS which in my case is a 530W. The moment it does not see the panel mounted GPS it will become active and provide you with all GPS data (GS, TRK, GPS ALT, position) and allow you to go direct to a waypoint. The "direct" button is grayed out whenever it is inactive.

 

What did your groundspeed show on your panel mounted GPS navigator? 

Ground speed and gps reception showed accurate according to the logs. 

[jlunseth]

Great. So we have an unexplained failure mode where the dual reversionary 275 set-up fails all AI. That would be really great in IMC. 173 seconds left. To cure it you need to either keep your vacuum or buy and install a third electric AI of a different, non-Garmin technology.

[Fly_M20R]

On 8/20/2021 at 11:21 PM, RobertGary1 said:

Ground speed and gps reception showed accurate according to the logs. 

Did you see the GS fluctuate a lot in your GPS Navigator?

[RobertGary1]

On 8/21/2021 at 5:42 AM, jlunseth said:

Great. So we have an unexplained failure mode where the dual reversionary 275 set-up fails all AI. That would be really great in IMC. 173 seconds left. To cure it you need to either keep your vacuum or buy and install a third electric AI of a different, non-Garmin technology.

Fortunately I kept my vacuum attitude. Couldn’t find any reason to remove it. Never ruined my day having too many attitude indicators.