Sign in to follow this  
Followers 0

Compass Interference 280 to 310 degrees

14 posts in this topic

Posted

Trying to calibrate my dash mounted compass (above dash).  This thing calibrates fine in all directions other than 280 to 310 degrees (using the adjustment screws).  In that range it is all over the lot (like +/- 20 degrees).  I have tried another compass (different style without compensation mechanism) with the same result (I also moved this around the cockpit with little change).  This is with and without electrical power or engine on or off.  Just something real strong causing an interference.

Any of you guys run across this?  Maybe the engine magneto/flywheel or starter causing a magnetic field?  I have a 582 with firewall mounted starter.  Just ordered some compass shielding material from Aircraft Spruce to see if I can do anything here.

Share this post


Link to post
Share on other sites

Posted

My compass just spins around in circles most of the time.

2 people like this

Share this post


Link to post
Share on other sites

Posted

My compass just spins around in circles most of the time.

Thats just your flying style, just go straight once :)

1 person likes this

Share this post


Link to post
Share on other sites

Posted

My compass just spins around in circles most of the time.

Thats just your flying style, just go straight once :)

Maybe he is in formation with circling California buzzards?  Sorry Larry, for injecting some Joey humor into your problem - I don't have a clue.  EDMO

Share this post


Link to post
Share on other sites

Posted (edited)

Lsaupe,  That sounds like a hard iron error.  Are you able to relocate the compass?  There is something to the (probably to the right of it) that is disrupting the magnetic field. 

 

Edited by Knuckledragger

Share this post


Link to post
Share on other sites

Posted

My compass just spins around in circles most of the time.

+1 on this one.  At any given time my compass is accurate to a heading within 360 degress of where it should be....  I gave up

1 person likes this

Share this post


Link to post
Share on other sites

Posted

mine does the same thing.. till I flip the radio on.. then it seems to tell me I am flying at 030 no matter what way the nose is pointed.  When I rebuilt mine I used a mag yoke and a gauss meter to get the tubing in the cockpit area to 0.  In the past this has worked on many super cubs that I have done for guys.  No dice on the Avid.  It could be the magneto or starter in close proximity to the compass that is hosing it up I gave up on it.  I fly VFR or IFRR (i follow roads or rivers) with mine.  I have the GPS in the dash and back up apps on my phone and tablet so I pretty muich know where I am going most of the time this way :lol:

 

:BC:

 

Share this post


Link to post
Share on other sites

Posted (edited)

Thanks for all the feedback.  The driver here is being able to do XC work sans hand held GPS for my PPL.  The bride tends to keep the 150 in use right now so am trying to enlist the Fox.  Knuckledragger - yep I have moved it around quite a bit with little change. I did receive the magnetic shield material from Spruce so will play with it this weekend a bit.  Or... just not fly on a course 280-310 :o)

Edited by LSaupe

Share this post


Link to post
Share on other sites

Posted

I messed around with installing the magnetic shield today.  It did a great job.  But, yep, something on the right side of the bird is messing things up.  Had to move it (the shield) as far right as possible (under the dash) to get an effect, but now have a real nice response around the full range.  Still can't figure what what the source is.  At least I have a band aid for it now.  Had a nice XC flight scheduled for tomorrow, but the airfield has turned into quicksand now that the frost is out.   The deer cant even get across now.  Hopefully better days ahead. 

1 person likes this

Share this post


Link to post
Share on other sites

Posted

The previous owner of my plane had solved it by putting a vertical card compass on the windscreen.  I am not a fan of having anything blocking my view out the front so I did not put it back in when I rebuilt mine.  I will have to look into the magnetic shield as it would sometimes be helpful to have something old school to point the way home.

:BC:

 

Share this post


Link to post
Share on other sites

Posted (edited)

Excuse my ignorance, but what is a magnetic shield?  If they were on a factory plane, then I must have missed class that day!   I like the vertical card compass mounted in the middle - from the seat on either side you should be able to see enough to keep between the telephone poles....   EDMO

Edited by EDMO

Share this post


Link to post
Share on other sites

Posted

The shield disrupts an errant magnetic field.  It is a thin sheet, 80% or so nickel.  Put it between your compass and the offending field.

3 people like this

Share this post


Link to post
Share on other sites

Posted

LSaupe,  have you tried doubling up on the shielding material?  Also, at some point you'll reach diminishing returns and then its time to calibrate and record the offsets on a card.

Share this post


Link to post
Share on other sites

Posted

Thanks for the feedback.  I could have (added another layer), but it showed good calibration with just one.  I calibrated and recorded on the placard deviation card so hopefully are good to go now. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0