GRT Avionics

Folks,
I'm getting a GNAV LOST error message on my EFIS HX display every once in awhile. I'd like to understand more behind what is driving this error message.

I'm selecting GNAV, and have selected the GTN650 as my GPS source.

I get the message when I'm in Laterial A/P mode...and trying to use the system per the manual instructions on page 5-3 of the 25 Sept 2015 User Manual.

To select LAT A/P- GNAV:
1. Press PFD button
2. Press NEXT button (more than once may be required)
3. Press LAT A/P GNAV. The EFIS passes roll commands from the 430(W)/530(W)/480 to the autopilot. Vertical steering commands are EFIS generated. This entry will only appear when the ARINC GPS Input setting is configured for the selected GPS receiver. It will turn gray when roll commands are not being received from the GPS. If GNAV is selected and roll commands are lost, GNAV LOST will flash on the screen.


Any ideas on what settings I need to check to eliminate this from popping up? What would cause it to appear at times, and NOT at other times?

Thanks,
Howard (Glastar N19HL w/ 122 hours and counting!)

As it says, the signals are not getting thru. I'd check:
Does the gps itself show a loss of signal? Assuming 'no' I would look for an intermittant connection (the worse to trouble shoot) in the ARINC lines from the GTN to the Hx.

Thanks Bob. I'll have to check for GPS signal the next time this comes up. I'm also going to double check my ARINC and AutoPilot settings for Lateral A/P.

Just wondering as well if anyone else out there has run into the "GNAV LOST" message popping up on their EFIS screen?

Howard

hplevyak wrote:Thanks Bob. I'll have to check for GPS signal the next time this comes up. I'm also going to double check my ARINC and AutoPilot settings for Lateral A/P.

Just wondering as well if anyone else out there has run into the "GNAV LOST" message popping up on their EFIS screen?

Howard

Yes, if I bank over 50 degs the Garmin 430W will lose signal lock, it comes back within 3 to 5 mins.