Magnetometer and AP servo

[charliesolo]

I am currently assisting my APIA in the installation of a Skyview system in my C172 and we have an area of disagreement. Now I know that he is the APIA and I am not, but I have installed Skyview systems in two of my EAB planes, and have assisted others in installs in six other EAB aircraft. In every install, we have taken care to locate the magnetometer in a known neutral location---generally out in a wing.

For the current Cessna install, the APIA wants to use the avionics shelf. Which is directly above the pitch servo. So the magnetometer is only separated from the pitch servo by about 3 inches and a thin piece of aluminum.

Is the Dynon servo magnetically "quiet" enough to allow this? I would love to be wrong about this... it is an otherwise ideal location.

Thanks in advance

 

[Marc_J._Zeitlin]

For the current Cessna install, the APIA wants to use the avionics shelf. Which is directly above the pitch servo. So the magnetometer is only separated from the pitch servo by about 3 inches and a thin piece of aluminum.

Is the Dynon servo magnetically "quiet" enough to allow this? I would love to be wrong about this... it is an otherwise ideal location.

The installation manual is very clear that the remote magnetometer should be mounted far away from magnetic material, high current wiring, and motors. Putting it on the avionics shelf near the stepper motor in the servo is probably about the worst place in the plane to mount it. As you surmise, out in the wing, or in the tail, or far away from the stuff mentioned above is best.

Your A&P/IA needs to read the manual, and some references on magnetic interference.

 

[Rhino]

Or get a new A&P.

 

[Dynon]

You are correct. 3" away from a Dynon AP servo is not far enough away. It will definitely interfere and cause substantial errors in magnetic heading detection.

 

[jakej]

Or get a new A&P.

Give me strength -it's hard enough to get some Dynon owner/users to read the manuals, much less chance of an A&P doing that- that would mean they'd have to go to the dark side

 

[BobMF8]

Download a compass app onto your cell phone. Your cell phone uses the same sensing method as your magnetometer only the magnetometer is much more sensitive. In your discussion with the A&P simply put your cellphone as close as he wants to place the mag in the panel from a radio antenna and key the mic. My phone shows the compass moves just a bit when my mic is keyed. Any mag is much more sensitive than the phone so if that doesn't convince him that distance matters I don't know what else to say.