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Degaussing

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tshort

Joined: 21 Oct 2017
Posts: 12

Posted: Wed Apr 25, 2018 12:44 am Post subject: Degaussing

The aft mounted magnetometer in my RV 10 has failed interference testing, only when the rudder moves. 



Garmin tells me I need to degauss the rudder cables. 



Anyone have suggestions on how to do so?

rv10pro(at)gmail.com
Guest

Posted: Wed Apr 25, 2018 1:22 am Post subject: Degaussing

Start with a simple  (Free)Android phone app

Such as Gauss Meter by Keuwlsoft.  It will help locate or confirm the item that becomes mangetized.



A degauss process is a coil of wire which creates a demagnetize field when switched on.  They were commonly used by TV techs in the 60s -70s to remove interference in Cathode Ray color picture tubes back in the day.



John Cox



On Wed, Apr 25, 2018, 01:50 tshort <tmshort(at)gmail.com (tmshort(at)gmail.com)> wrote:



 	  Quote: 	
		  --> AeroElectric-List message posted by: "tshort" <tmshort(at)gmail.com (tmshort(at)gmail.com)>

 

 The aft mounted magnetometer in my RV 10 has failed interference testing, only when the rudder moves. 

 

 Garmin tells me I need to degauss the rudder cables. 

 

 Anyone have suggestions on how to do so?

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=479541#479541

 

 

 

 

 

 

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user9253

Joined: 28 Mar 2008
Posts: 1926
Location: Riley TWP Michigan

Posted: Wed Apr 25, 2018 4:52 am Post subject: Re: Degaussing

Try a soldering gun (NOT a soldering iron).  Remove the two screws that hold the heating element.  Put the heating element around the rudder cable and reassemble the soldering gun.  Turn on the soldering gun and slowly move it along the rudder cable, being careful not to burn yourself or anything else.

I have never done this and have never heard about others doing it.  But hey, it is worth a try.

_________________
Joe Gores

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Wed Apr 25, 2018 5:35 am Post subject: Degaussing

Hello Shorty:

Very Interesting!

In the good old days it was very easy to make a Degaussing Coil (D-C), actually the coil was already made for you and all you had to do was hook up 110 VAC.

The Coil was the DEFLECTION COIL on the back of the old TV's...  It is the large coil that slipped over the shank of the CRT... Cathode Ray Tube.   

All that a D-C is, is a very long length of a coil of wire.  To the ends of the coil you apply 110 VAC through a PUSH BUTTON switch.  It continuously reverses the magnetic fields at the rate of 60 times per second (60 Hz).  The coil is then slowly moved in ONE DIRECTION along the length of the item you wish to demagnetize.

OK, lets prove the cables are magnetized.  I doubt it!  Why?  Because the cable are made of a low ferrous metal.  The cables are advertised as Stainless Steel (S/S).  True, not all S/S is non-magnetic.

Start with a COMPASS - Move the compass along the length of the cables and of course the STEEL pivot points.  The Compass will point directly to the magnetized item. 

  Sounds like you are installing a G5 system?  



ALSO...  Go back and watch your DG/HSI as you move the rudder peddles.  The Heading should change as the peddles are moved.  Move them slowly from stop to stop.  My SWAG is:  If the Heading does NOT change - Don't worry about it, you are good to go!  The test procedure is way more sensitive/selective than the Magnetometer and the DG/HSI.

If the DG/HSI does move then YES - Use the D-C.

Side Note:  You can also do as ships do:  Fly a course in direct Opposition to the magnetic fields of the earth.  This is used to Degauss the ship...  in your case the plane (ship).  Look up Ship Degaussing procedures - Check out "The Chapman's  Manual".

Since there are very few old TV's which you can steal a coil from let's move to your next options.

1 - Look for a place where you can purchase or rent a D-C.  Look at the old electronic shops.

2 - Obtain a ROLL of INSULATED wire - 24 to 34 AWG about 1,000 Ft.  You will have to have access to BOTH ends of the wire.  Then all you have to do connect a 110 VAC line and a Push Button Switch to the ends.  The go GAUSS!

Best of luck,

Barry





On Wed, Apr 25, 2018 at 4:44 AM, tshort <tmshort(at)gmail.com (tmshort(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "tshort" <tmshort(at)gmail.com (tmshort(at)gmail.com)>

 

 The aft mounted magnetometer in my RV 10 has failed interference testing, only when the rudder moves. 

 

 Garmin tells me I need to degauss the rudder cables. 

 

 Anyone have suggestions on how to do so?

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=479541#479541

 

 

 

 

 

 

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 eferrer" target="_blank">http://forums.matronics.com

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BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Wed Apr 25, 2018 5:36 am Post subject: Degaussing

WOW!  GREAT TRICK JOE!!!  GREAT TRICK!

Barry

On Wed, Apr 25, 2018 at 8:52 AM, user9253 <fransew(at)gmail.com (fransew(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com (fransew(at)gmail.com)>

 

 Try a soldering gun (NOT a soldering iron).  Remove the two screws that hold the heating element.  Put the heating element around the rudder cable and reassemble the soldering gun.  Turn on the soldering gun and slowly move it along the rudder cable, being careful not to burn yourself or anything else.

 I have never done this and have never heard about others doing it.  But hey, it is worth a try.

 

 --------

 Joe Gores

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=479544#479544

 

 

 

 

 

 

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nuckolls.bob(at)aeroelect
Guest

Posted: Wed Apr 25, 2018 11:37 am Post subject: Degaussing

Try a soldering gun (NOT a soldering iron).

 Remove the two screws that hold the heating

 element. Put the heating element around the

 rudder cable and reassemble the soldering gun.

 Turn on the soldering gun and slowly move it

 along the rudder cable, being careful not to

 burn yourself or anything else.



 I have never done this and have never heard

 about others doing it. But hey, it is worth a try.

   



   It works. I've used the soldering gun to

   demag small tools. There are several articles

   on the 'net for doing similar tasks.



    



   Here the author made up a coil of longer

   wire (gives stronger field with less heating).



   One could take a piece of bare 12AWG copper

   and form it 4-5 turns around the target

   material before reconnecting to the soldering

   gun.  I've measured the current in stock

   Weller tips at over 200 amps. So using

   the single-turn of a stock tip would

   give you 200+ ampere-turns of flux.



   Fabricated coils will be higher 

   resistance but if you can get 150A

   through 5 turns, your degaussing flux

   rises to 750AT.



 

   Bob . . .

skywagon

Joined: 11 Feb 2006
Posts: 184

Posted: Wed Apr 25, 2018 11:51 am Post subject: Degaussing

. . . any chance there is other electronics "back" there that are  operational, such as tail strobe and power supply causing interference with  flux..??  

  

   

 [quote]   ---

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Apr 25, 2018 6:51 pm Post subject: Degaussing

At 02:49 PM 4/25/2018, you wrote:

  	  Quote: 	
		   

 . . . any chance there is other electronics "back" there that are operational, such as tail strobe and power supply causing interference with flux..??  	


   Excellent question. I am skeptical of the notion

   that control cables have become magnetized . . .

   and if they were, they would have to carry

   flux lines longitudinally . . . i.e. little

   to no discernable changes in magnetic field

   as the cables operate to affect rudder

   position.



   But if moving the rudder has an observable

   effect, then there has to be a foundation

   in physics for the observation.



   On the other hand, does it matter? If

   the magnetic compass feature is 'swung'

   with the rudder centered . . . what

   is the probability of introducing a

   critical error into the system's magnetic

   nav data with a large rudder excursion?

   Most autonomous attitude tracking involves

   very small excursions of flight controls.

   If rudder motion was a source of error, just

   how often and under what conditions would

   that error manifest? 



 

 

   Bob . . .

ronaldcox

Joined: 24 Jan 2008
Posts: 40

Posted: Thu Apr 26, 2018 7:52 am Post subject: Re: Degaussing

 	  nuckolls.bob(at)aeroelect wrote: 	
		  Try a soldering gun (NOT a soldering iron).

 Remove the two screws that hold the heating

 element. Put the heating element around the

 rudder cable and reassemble the soldering gun.

 Turn on the soldering gun and slowly move it

 along the rudder cable, being careful not to

 burn yourself or anything else.



 I have never done this and have never heard

 about others doing it. But hey, it is worth a try.

   



   It works. I've used the soldering gun to

   demag small tools. There are several articles

   on the 'net for doing similar tasks.



    



   Here the author made up a coil of longer

   wire (gives stronger field with less heating).



   One could take a piece of bare 12AWG copper

   and form it 4-5 turns around the target

   material before reconnecting to the soldering

   gun.  I've measured the current in stock

   Weller tips at over 200 amps. So using

   the single-turn of a stock tip would

   give you 200+ ampere-turns of flux.



   Fabricated coils will be higher 

   resistance but if you can get 150A

   through 5 turns, your degaussing flux

   rises to 750AT.



 

   Bob . . . 	




I wonder if an old magnetic tape eraser would work. 



I have one that I used to use to erase magnetic tapes, and I'll bet that would work. If you can find one in a second-hand shop, that might work. Might even be easier to find than a soldering gun! 

Mine looks like a small clothes iron encased in a plastic box with a handle and a trigger.



Used to use it for VCR tapes, audio tapes, and computer backup tapes when the need arose. I've seen them in the aircraft aisle at the local Salvation Army store.  



Also, it wouldn't have to be the cable that's magnetized.  As others have said, that's unlikely.  But it could be a steel bolt, or possibly bell-crank or swaged-on fitting.



I'm trying to think of other things in that area that would be ferrous metal, but there isn't much in most planes.  There's the hinge pin, but that wouldn't change position with rudder movement.



Just another possible solution.



Ron

_________________
Ron Cox
Glasair Super II F/T
Under Construction at C77 - Still just about to fly!

tshort

Joined: 21 Oct 2017
Posts: 12

Posted: Fri Apr 27, 2018 2:28 am Post subject: Re: Degaussing

Thanks for all the replies.



I am virtually certain it is the cables:



- the test passes on all other parameters (turning off / on all the equipment in the tailcone, etc etc).  The test shows significant error as soon as I move the rudder at all.



- I downloaded an app for the phone (per the suggestion above), and it does detect magnetic fields near the cables.



Since we had already reassembled things and had the bag wall back in, I used the solder iron technique on the cable ends and cable outside of the tailcone.  Measurements before and after with the phone app did show less detected.



Finally, I calibrated the magnetometer as per Garmin's instructions.  With ground testing and test flying yesterday, I saw zero movement of the indicator with any rudder input.



Since I am flying VFR only, I am going to continue to monitor / test fly, and next time I have occasion to get back in the tailcone I may make some additional efforts at degaussing.

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Fri Apr 27, 2018 6:31 pm Post subject: Degaussing

Shorty:

A COMPASS will literary Point at the problem.

And, if the magnesium is very high you should be able to do it from the outside of the plane.  The aluminum will offer very little shielding.

Barry

On Fri, Apr 27, 2018 at 6:28 AM, tshort <tmshort(at)gmail.com (tmshort(at)gmail.com)> wrote:

 	  Quote: 	
		  --> AeroElectric-List message posted by: "tshort" <tmshort(at)gmail.com (tmshort(at)gmail.com)>

 

 Thanks for all the replies.

 

 I am virtually certain it is the cables:

 

 - the test passes on all other parameters (turning off / on all the equipment in the tailcone, etc etc).  The test shows significant error as soon as I move the rudder at all.

 

 - I downloaded an app for the phone (per the suggestion above), and it does detect magnetic fields near the cables.

 

 Since we had already reassembled things and had the bag wall back in, I used the solder iron technique on the cable ends and cable outside of the tailcone.  Measurements before and after with the phone app did show less detected.

 

 Finally, I calibrated the magnetometer as per Garmin's instructions.  With ground testing and test flying yesterday, I saw zero movement of the indicator with any rudder input.

 

 Since I am flying VFR only, I am going to continue to monitor / test fly, and next time I have occasion to get back in the tailcone I may make some additional efforts at degaussing.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=479589#479589

 

 

 

 

 

 

 ====================================

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  FORUMS -

 eferrer" target="_blank">http://forums.matronics.com

 ====================================

 WIKI -

 errer" target="_blank">http://wiki.matronics.com

 ====================================

 b Site -

           -Matt Dralle, List Admin.

 rel="noreferrer" target="_blank">http://www.matronics.com/contribution

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