Garmin 430 Loss of Integrity Message

[Rivermoney]

New to Mooney ownership here. Have flown about 25 hours the past month to get current and the last two flights began to get a 'loss of integrity' message on the Garmin 430. The message is intermittent and came on approximately 5-7 times over two two hour flights (one was IPC). The system returned to normal each time. General flying location was in the Maryland area in a triangle bounded by Hagerstown, MD, Gaithersburg, MD, and York, PA. No issues observed on unit startup. I am using a homemade Stratux ADS-B In while flying. I see very little information on the web regarding this and no 'troubleshooting' in the original Garmin 430 manual that came with the AC. No other known EMI generated on the AC. Mobile phone is turned off. iPad mini is on for ADS-B in and Foreflight - no SIM card. Thanks. 

[mattbucy]

Might be a long shot, but I had a similar problem not long ago. Pulling the 430 out and reseating it solved the problem. Mine might have been a little loose after panel work.

Edited March 30, 2021 by mattbucy

[Ragsf15e]

Potentially an antenna issue too.  Reseating it is a good idea.  How hard is it to check the connection to the antenna?

[carusoam]

Welcome aboard Wrein.

Any old Narco radios on board?

When tuned to certain nav frequencies, my Narco would be so noisy, it would knock out my GPS signals...

It was a challenge to figure out, until I passed through the same place twice... and got the same result...   

Consider anything onboard that is electrically noisy...

Ask your PO, if he had experienced this as well...

 

Another thing that has occurred before...   check the distances between antennas on the roof...

There is guidance on how far antennas need to be from each other to co exist...

In some installations, holes in the roof were improperly re-used...

Of course... don’t forget to check the notams for your area... sometimes GPS signals get altered for a reason...

PP thoughts only...

 Best regards,

-a-

[Rivermoney]

Thanks for the welcome. There is a MAC 1700 NAVCOM unit mounted just below the Garmin 430. The Garmin 'loss of integrity' message has only occurred in the last 4.5 hours of flights, both of which were my first set of true IFR flights where I tuned the MAC 1700 to provide a backup VOR signal. However, I have used the MAC 1700 as an additional COM unit for ATIS, AWOS, etc. for most of the flights since buying the plane in late Feb with no 'loss of integrity' message observed. 

The seller said he had the MAC 1700 'redone' two years ago but not sure what that means. The seller always flew IFR and owned the plane 28 years, hangered, with no apparent issues - he has been an open book for me. So, I do have a high trust in his experiences he relates to me. I will 'shut down' the MAC next time I fly through the same areas late this week/weekend and check it out. 

I will check ant distance though I suspect they are good with Garmin just above cockpit, VOR on tail fin, and comms on either side of Garmin but maybe four feet???  The seller added the Garmin in 2005, and it was a new mount area. 

Good idea on the NOTAMs. the areas, last two flights, are near the Camp David MD restricted areas...was my first thought (former military pilot here). 

I removed the cowl access panel just above the instruments this morning to check for any moisture or general 'cabling' issues. Everything was dry and no brittleness detected on wiring harnesses. I was also checking to learn the best way to remove and reseat the Garmin connections. Any advice on that would be appreciated.

My suggested order of system checks:

1. Check flight with MAC 1700 off in the same vicinity of known integrity message issues. Cycle it on and off with VOR freqs used before.

2. Reseat connections on Garmin unit first - I assume the ant is a pain to reseat as connection is accessed by removing ceiling panels????

 

 

 

 

 

 

 

[carusoam]

Also...

Find the GPS sat strength display...

Its probably a page of bar graphs on your Garmin...

You can experiment with a few things and see if anything affects the bars any...

 

I did this for my portable GPS... and could visually see the interruption...

PP thoughts only, not an avionics tech...

Best regards,

-a-

[rbridges]

On 3/29/2021 at 10:10 PM, Ragsf15e said:

Potentially an antenna issue too.  Reseating it is a good idea.  How hard is it to check the connection to the antenna?

That's what happened to mine. Bad antenna. 

[Rivermoney]

On the last flight while transiting through the geographical area in which I had the Loss of Integrity (LOI) message, I tuned the MAC 1700 Nav/Com to a nonexistent VOR. I observed no LOI issues on the Garmin. For the whole flight, down and back from DC to Raleigh, I did not use the MAC 1700 VOR - no Garmin issues. I did check the Sat strength and all was good. I have not yet reseated the connectors -- think I will wait until I see another LOI message...next flight I will turn MAC VOR back on and see if LOI resumes...didn't do that the other day, bad maintenance check pilot I was, on IFR plan and was getting vectored all over in DC area.  Thanks for all the tips. 

 

[MBDiagMan]

My first suspect would definitely be the antenna and it’s cabling.  When working on radar problems in the army, wiggling the coaxes commonly located source of noise and flaky signals.  Not scientific, but we had to get fire control radar systems back on the air FAST and that method was often successful.