Garmin G5 problem

[highlowfastslow]

On 6/7/2017 at 9:00 PM, AaronDC8402 said:

@highlowfastslow, do you know which version of firmware is on your G5? Supposedly, the updated firmware (v2.6) solved the issue you're describing. 

Had a chance to check today .It came installed with 2.7 so it should have had 2.6 upgrades when this happened. I upgraded to 3.2 today so we'll see if that helps. Either way, launching into IMC i'm taking the time to make sure it's up. It definitely didn't say ALIGNING when i took off though, so not sure how we're supposed to be able to tell it's not ready. 

[Avionicspro]

Hey guys I wanted to drop a few thoughts on this topic.  By no means am I negating any other suggestions here or sw/fw version comparisons.  I want to talk about the unbelievable importance of the installation.  In almost all the threads I read I see very little on this subject which makes me assume either all the installation data including alignment and interference issues have been negated on this topic or assumed accurate.  

Having installed Garmin equipment for years (go back to Apollo) I can't say enough about how critical understanding, identifying and correcting any issues found during the pre-installation tests.   With my background I have two areas that are continuously overlooked or not given their due respect.  #1 The GMU interference test and #2 leveling both vertically and laterally the units to level of flight.  These two items being done correctly will make the post-installation config/check-out process go smoothly and provide you the owner/operator reliable performance you've come to expect from Garmin.

Holding an AP/IA and a guy that flies, I take the little things serious because re-work sucks and safety is paramount.  I put these two items in that order for a reason.  Without the in-depth knowledge of what it takes to install one of these, most installers discount or ignore the interference failures because going back to the customer for additional labor hours is taboo.  And most operators don't know to ask or are told these are expect issues with this or that unit.  Therefore no re-work.  I haven't seen any complaints here on the topic of the shop needing to do additional work to make this happen.  As a safety item, well I think this thread speaks for itself.  Some of you either have them installed or are thinking about it and due to reliable performance issues you wouldn't think about using this a primary instrument.  To me that's a backwards way of looking at something that should be considered an "upgrade" from existing equipment not an addition to.  Additionally, this unit has provided flight data to the experimental market before becoming Part 23 certified.  You have to know if the feds even thought the unit was going to have reliability issues as a primary instrument you wouldn't even be having this conversation.     

So, onto our story here:

Garmin makes a point in all their manuals about how sensitive their units are and how important alignment is.  Working with all the other digital AHRS manufactures Garmin holds the trophy for being most critical and for interference, the most sensitive.  Guess that is good and bad.  The bad is what I'm going to speak to. 

All of Garmin's HDG/AHRS units have required interference testing before an installation can be accomplished.  This is one thing I've seen very little about in any thread.  When installing a digital anything it's important to understand these units operate on a data buss and are constantly communicating with each other.  If one has issues or reports bad data on the buss the other units can be impacted.  Case and point.  Installing the GMU-11 in our M20C we failed the interference test several times until we moved the strobe power ground from the shelf replacing it with a shielded wire run forward to the ground closer to the battery and isolated from the frame, replaced the hardware in the rudder bellcrank (pivot arm) and moved the ground for the tail strobe.  All items found BEFORE anything was hard-mounted.  Need to pay particular attention to the strobe power ground.  You will rarely find one that doesn't have the ground point at or next to the power supply itself.  This is one noisy bastard.  If any of this is in question the G5 can be run in maint mode and you can check out the results for yourself.  The GMU has 3dg +/- in both pitch and roll alignment to level flight.  HDG alignment is suggested to be .5dg.  Can some of this be mitigated or discounted as minimal system impact?  Yes I'm sure it can, but it's you flying in IMC not the guy on the ground.   

Now, the G5 installation.  You have 15dg on the longitudinal axis to play with but only 1dg of play in the vertical axis.  To complicate matters knowing all the numbers and doing the math is a pain.  For the record I don't like this approach.  As an installer taking the guess work out by jacking and leveling the plane and hitting the button is a whole lot easier and more accurate than how the G5 manual has you do it.  Which Mooney do you have?  The M20C has a tilt of 8dg, I understand the 20J is a zero tilt.  This needs to factored into the calibration equation.  Not going to bore you with the math, needless to say this step if done incorrectly will absolutely cause false indications.

Finally, if you are dissatisfied with the performance of your G5, before you blame anything get the facts.  The shop should be able to pull the work-order for your install and provide you with all the interference and alignment data for your plane.  You should keep these for your records.  You should also have this data should you require maintenance at another shop.  The ICA will require this information to validate installation vs. configuration.

Hope this helps shed some light.

 After we finish the install and get a few hours wheels-up I'll give an update. 

Bill T. 

[carusoam]

Welcome aboard, Bill.

When you get a chance, please update your avatar info.

It will help MSers get to know you better. This adds some context to your statements.

Best regards,

-a-

[bradp]

Bill I couldn't agree with you more having done the installation and calibration for my G5.  It was not hard but certainly painstaking work to jack and level the plane and double and triple check that the yaw axis was within spec.  In addition all the panel mount shocks were replaced just prior to the install, so making sure the panel face was actually perpendicular to the yaw axis was important.

There are a number of threads over on beechtalk where there's a picture of a skewed attitude indication (as above).  It probably comes down to the thing is not sitting perfectly flush or something has become jostled in the yaw axis.  The vertical axis is the easy one to at least get near / within spec unless you are dealing with a sloped panel like Bill mentions above.  The wonky attitude indication is identical to what happened when my flightstream 210 became a bit off center from it's mount - almost a skidding rolling indication.  For the early adopters there was an issue with firmware, but this has been resolved.  For these latter install problems the likelihood is that there is a installation or calibration issue.