Magnetic components in Garmin GMU11 connector kit!

[Hartstoc]

I’m in the middle of a major all-Garmin G3X/GTN panel upgrade. Installation instructions for the magnetometer element, the GMU 11, warn against putting it near any ferrous components, even recommending replacing any nearby steel screws or bolts with non-magnetic alternatives. I was pretty shocked to discover that that Garmins’s own installation kit for the GMU 11 contain large, highly magnetic screws and retainers! Worst offenders are huge, heavy, and completely pointless knurled thumbscrews whose only purpose is to make installation and removal of the D-sub connector easy(something you almost never do). I discarded all of these parts and will use nylon tie-wraps to secure the D-sub to the unit.

(Added note: be sure to read responses to this concern posted below by G3Xpert Steve.)

[snoop9erdog]

Originally Posted by Hartstoc

I?m in the middle of a major all-Garmin G3X/GTN panel upgrade. Installation instructions for the magnetometer element, the GMU 11, warn against putting it near any ferrous components, even recommending replacing any nearby steel screws or bolts with non-magnetic alternatives. I was pretty shocked to discover that that Garmins?s own installation kit for the GMU 11 contain large, highly magnetic screws and retainers! Worst offenders are huge, heavy, and completely pointless knurled thumbscrews whose only purpose is to make installation and removal of the D-sub connector easy(something you almost never do). I discarded all of these parts and will use nylon tie-wraps to secure the D-sub to the unit.

Ditto that. I guess I'll need to do the same. What have others done with the connector kit of the GMU11?

[lr172]

I doubt it's an oversight. I am sure the calibration will factor out those static parts. It's the moving magnetic parts that really mess it up, like seat belt cables and elevator horns.

Garmin seems too large and thorough to make a mistake like that. Without understanding the details of how an electronic magnetic sensor and it's associated software acquires a heading, it seems unfair to say they have done something wrong.

Larry

[BobTurner]

Originally Posted by lr172

Garmin seems too large and thorough to make a mistake like that.
Larry

Everyone makes mistakes. Sometimes it?s the simplest and obvious that slip thru.

[g3xpert]

Originally Posted by lr172

I doubt it's an oversight. I am sure the calibration will factor out those static parts. It's the moving magnetic parts that really mess it up, like seat belt cables and elevator horns.

Garmin seems too large and thorough to make a mistake like that. Without understanding the details of how an electronic magnetic sensor and it's associated software acquires a heading, it seems unfair to say they have done something wrong.

Larry

Thank you Larry. You are correct. No oversight.

During our initial development and prototyping of the GMU 11 magnetometer, we were very concerned about the possible impact of having a connector with metal backshell, and in some cases a CAN terminator attached to the end of the GMU 11.

We didn't actually know if we would be able to use this design, but fortunately, all testing proved that the impact was negligible. This was good news since we feel it is important for the CAN bus shield to attach to the metal backshell at each device, and this is done with the GMU 11 as with all other CAN devices. We have a great many successful installations, some in certified aircraft with the G5 and GFC 500 autopilot.

We certainly don't believe that it is normal for this connector kit to be magnetized, and we tested a new kit today just as a sanity check and found nothing to be magnetized.

It is very important to keep all metal hardware used with a magnetometer installation away from magnets or magnetized tools to make sure that these installation materials do not become magnetized.

Thanks,
Steve

[Hartstoc]

Originally Posted by g3xpert

Thank you Larry. You are correct. No oversight.

During our initial development and prototyping of the GMU 11 magnetometer, we were very concerned about the possible impact of having a connector with metal backshell, and in some cases a CAN terminator attached to the end of the GMU 11.

We didn't actually know if we would be able to use this design, but fortunately, all testing proved that the impact was negligible. This was good news since we feel it is important for the CAN bus shield to attach to the metal backshell at each device, and this is done with the GMU 11 as with all other CAN devices. We have a great many successful installations, some in certified aircraft with the G5 and GFC 500 autopilot.

We certainly don't believe that it is normal for this connector kit to be magnetized, and we tested a new kit today just as a sanity check and found nothing to be magnetized.

It is very important to keep all metal hardware used with a magnetometer installation away from magnets or magnetized tools to make sure that these installation materials do not become magnetized.

Thanks,
Steve

Steve- Thank you for these clarifications. I should add one- by “highly magnetic” I was not refering to components that are magnetized, but ones that are strongly attracted to a magnet. I checked the standard-issue massive Garmin backshell kit supplied for the GMU11 and discovered the needlessy large retaining screws(essentially micro-screws each with a large steel screwdriver built right in!) to be so.



The concern here, as with other nearby steel components Garmin warns against, is that this material could affect precision by altering magnetic flux behavior in the immediate vicinity of the GMU11. In spite of your reassurances, it still seems to me that doing anything possible to reduce this influence is worthwhile, such as replacing these retainers with tiny stainless steel or plastic screws, or using tiewraps or vinyl tape to secure the d-sub to the unit. Would you argue otherwise?- Otis

[g3xpert]

Originally Posted by Hartstoc

Steve- Thank you for these clarifications. I should add one- by ?highly magnetic? I was not refering to components that are magnetized, but ones that are strongly attracted to a magnet. I checked the standard-issue massive Garmin backshell kit supplied for the GMU11 and discovered the needlessy large retaining screws(essentially micro-screws each with a large steel screwdriver built right in!) to be so.



The concern here, as with other nearby steel components Garmin warns against, is that this material could affect precision by altering magnetic flux behavior in the immediate vicinity of the GMU11. In spite of your reassurances, it still seems to me that doing anything possible to reduce this influence is worthwhile, such as replacing these retainers with tiny stainless steel or plastic screws, or using tiewraps or vinyl tape to secure the d-sub to the unit. Would you argue otherwise?- Otis

Hello Otis,

No concern at all with following the installation instructions. I have the GMU 11 installed at the end of the CAN bus in my plane, so I have the connector, backshell, and CAN terminator installed, and everything works great.

LOTS of testing involved with coming up with the GMU 11 automated factory calibration procedures, and they all use this connector.

Keep magnets away from the hardware, mount it like instructed, and it will work great.

Thanks,
Steve

[Hartstoc]

Originally Posted by g3xpert

Hello Otis,

No concern at all with following the installation instructions. I have the GMU 11 installed at the end of the CAN bus in my plane, so I have the connector, backshell, and CAN terminator installed, and everything works great.

LOTS of testing involved with coming up with the GMU 11 automated factory calibration procedures, and they all use this connector.

Keep magnets away from the hardware, mount it like instructed, and it will work great.

Thanks,
Steve

Thanks, Steve- it is good to have clarity on this. So, if I understand correctly, all other nearby ferrous materials are bad, but these particular bits of steel are good because factory system calibration includes them, and their omission would decrerease rather than increase precision, correct? - Otis

[RVbySDI]

Originally Posted by Hartstoc

Thanks, Steve- it is good to have clarity on this. So, if I understand correctly, all other nearby ferrous materials are bad, but these particular bits of steel are good because factory system calibration includes them, and their omission would decrerease rather than increase precision, correct? - Otis

Not sure where this thread is going. For that matter, don't know where it is coming from either. You have a direct reply (actually two direct replies) from THE Garmin representative telling you the low down on your concern. So you don't believe him? If not, then why are you using their product?

[Hartstoc]

Originally Posted by RVbySDI

Not sure where this thread is going. For that matter, don't know where it is coming from either. You have a direct reply (actually two direct replies) from THE Garmin representative telling you the low down on your concern. So you don't believe him? If not, then why are you using their product?

Well, As a thinker, reality always trumps guidance for me because the one is perfect while the other can be flawed. Thanks to Steve?s responses, I?ve concluded that it is best to follow guidance in this instance and will install the GMU 11 per Garmin instructions . I do think my point was valid though, as I discovered components within the standard-issue Garmin backshell connector which appeared to violate Garmin?s own warning against nearby ferrous materials.

I also edited-in a note at the bottom of my original post asking readers to be sure to read Steve?s comments.- Otis