Where to install a magnetometer ?

[OR75]

For those with a magnetometer , where is it located ? 

I understand it needs to be as far as possible from servos and high current equipments 

I have an S-tec pitch servo in the tail cone and strobes (classic and not LED type) at the wingtips ? 

Left wing has a servo for the century IIB and the pitot tube ( high current when heated I suspect) 

Thoughts ? 

 

 

 

 

[HRM]

Mine is up in the top of the center of the tail.

[OR75]

Wow, how did one come up with that ?

my thinking was the avionics rack or near an inspection panel in a wing 

[kortopates]

The factory installs them in the left wing where the AP servo would go except its in the Right wing.


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[HRM]

40 minutes ago, OR75 said:

Wow, how did one come up with that ?

50 odd years ago. Newer magnetometers are less "steam-punky" 

[carusoam]

If you are looking for the one you have...

It is hiding behind the access panel that has brass looking rivets(?) not sure why my rivets on that panel are brass looking.

Best regards,

-a-

[OR75]

I don't have one . Thinking ahead about where the magnetometer fur the G5 will need to be installed 

[N201MKTurbo]

On ‎7‎/‎23‎/‎2017 at 7:43 PM, OR75 said:

I don't have one . Thinking ahead about where the magnetometer fur the G5 will need to be installed 

I'm doing the exact same thing. Mounting to a wing panel is worrisome because of the screws and nut plates. The tail cone is probably the surest thing. Let me know what you come up with.

[carusoam]

Screws and nut plates get swapped out for different hardware (rivets) when the magnetometer is factory mounted in the wing...

The oddity of these rivets seem to be the material they are made of...  They look like brass rivets on mine(?)

Not sure why an aluminum rivet wouldn't do,  Or what I am really looking at...

Best regards,

-a-

[jetdriven]

Right wing about halfway out. Rear set of inspection panels, because the strobe wiring and the steel aileron pushrod are in th front third of the wing.  Rivet the bracket to the Rib. 

Edited July 28, 2017 by jetdriven

[N201MKTurbo]

14 minutes ago, jetdriven said:

Right wing about halfway out. Rear set of inspection panels, because the strobe wiring and the steel aileron pushrod are in th front third of the wing.  Rivet the bracket to the Rib. 

If I put it in the wing, I was thinking about putting it on long aluminum spacers to get it as close to the top of the wing as I could. Easier than riveting a bracket.

[jetdriven]

Needs to be on solid mount and not able to disturb. Rivets to a rib are a good solution.  The spacers would have to be 2-4" long,  then you would not have a rigid compass mount 

Edited July 28, 2017 by jetdriven

[Browncbr1]

I have a remote electric compass magnetometer at the roof of my tail...  no problems years with my oem rotating beacon and strobe on the floor of the tail cone.

[N201MKTurbo]

1 hour ago, jetdriven said:

Needs to be on solid mount and not able to disturb. Rivets to a rib are a good solution.  The spacers would have to be 2-4" long,  then you would not have a rigid compass mount 

I must have better spacer than you. I can't imagine it moving. To make the bracket I would have to drive down to Tucson to get access to sheet metal tools.

[jetdriven]

added pics above

[ArtVandelay]

46 minutes ago, jetdriven said:

added pics above

It doesn't look level?

[OR75]

8 hours ago, N201MKTurbo said:

I'm doing the exact same thing. Mounting to a wing panel is worrisome because of the screws and nut plates. The tail cone is probably the surest thing. Let me know what you come up with.

The install manual specifically says you cannot install on an inspection panel . It does not have to be a level surface though

[N201MKTurbo]

12 minutes ago, OR75 said:

The install manual specifically says you cannot install on an inspection panel . It does not have to be a level surface though

Well you are half right. I don't know why the prohibition on the access panel other than the nut plates. In a Mooney wing you can't get too far from them.

It says it must be level to within 3 degrees.

[OR75]

2 hours ago, N201MKTurbo said:

Well you are half right. I don't know why the prohibition on the access panel other than the nut plates. In a Mooney wing you can't get too far from them.

It says it must be level to within 3 degrees.

The install manual does not elaborate on why it cannot be on an inspection panel but I suspect that the device must be permanently fixed while an inspection panel can be turned . Not sure to be honest 

leveling within 3 degrees is probably not too difficult to achieve with washers not sure why it would be so critical . The heading is still indicated in a bank , right ? But I am don't understand the technology 

[takair]

19 minutes ago, OR75 said:

The install manual does not elaborate on why it cannot be on an inspection panel but I suspect that the device must be permanently fixed while an inspection panel can be turned . Not sure to be honest 

leveling within 3 degrees is probably not too difficult to achieve with washers not sure why it would be so critical . The heading is still indicated in a bank , right ? But I am don't understand the technology 

I think there are a few reasons for not installing it on a panel.  One, there are often steel nut plates installed, which can influence the magnetometer. However, as others alluded, repeatability is difficult when installed to a plate that may be removed.  Technically you would need to do a compass swing each time you had it out.

Regarding turns, the heading comes from the gyro.  The magnetometer has less influence in turns and typically does its work over a longer period of time....mostly in straight and level...unaccelerated flight.  

Ideally, you want it two to three feet from motors, steel, high current, etc. for optimal performance and ease of alignment.  

[N201MKTurbo]

18 minutes ago, OR75 said:

The install manual does not elaborate on why it cannot be on an inspection panel but I suspect that the device must be permanently fixed while an inspection panel can be turned . Not sure to be honest 

leveling within 3 degrees is probably not too difficult to achieve with washers not sure why it would be so critical . The heading is still indicated in a bank , right ? But I am don't understand the technology 

The same reason the compass goes crazy in a turn. The magnetic lines of force have a vertical component. They point down at the poles.

[HRM]

Well, after all the yak on this, did anybody ask Garmin or one of the big avionics shops? Surely they would know the optimal location for a Mooney--they are all pretty much the same. The manual goes into quite a bit of detail on mounting as well as interference testing prior to final install.

Here is what the G5 unit (GMU 11) looks like:

[jamesm]

The Garmin GMU 11 has an interference test that you run to see if location chosen is acceptable. The inference test is ran off the G5  display and works  pretty slick.   My first choice was in tail section far  right side where the old tube power supplies  were mounted opposite radio access panel. It  failed the interference  test. moved to the GMU-11 to the  far left  side it passed. Other  than slight  over sight in the install manual. OBTW Figure 1-4 is incorrect The GMU 11 is a DB9  connector not a 15 DB connector (as shown  above).  

James '67C

[OR75]

1 hour ago, jamesm said:

The Garmin GMU 11 has an interference test that you run to see if location chosen is acceptable. The inference test is ran off the G5  display and works  pretty slick.   My first choice was in tail section far  right side where the old tube power supplies  were mounted opposite radio access panel. It  failed the interference  test. moved to the GMU-11 to the  far left  side it passed. Other  than slight  over sight in the install manual. OBTW Figure 1-4 is incorrect The GMU 11 is a DB9  connector not a 15 DB connector (as shown  above).  

James '67C

Is that the avionics rack ? 

[jetdriven]

On 7/28/2017 at 6:16 PM, teejayevans said:

It doesn't look level?

It must be wirhin like 2 degrees of level in the flight attitude. The airplane is 2 degrees ANU on the ground plus it has about  1.5 degrees of dihedral. The rib is not parallel to the ground.  Spacing it on the top rivets  and rotating it on the rib gets it at zero/zero when it's on jacks on the flight attitude.