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Permalink Reply by Bob McDonald on August 15, 2012 at 8:49pm

Post a picture of how it is mounted. Is in in the panel or on top of the glareshield ? Mine is mounted above the glareshield with the bracket Aircraft Spruce sells... no problems. I have one in my CH601HD and one in my CH750.

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Permalink Reply by Luzius Thoeny on August 15, 2012 at 9:13pm

Dont have apicture right now. Its mounted on top of instrument pannel I made the bracket  out of .050 6061-T6. It does not mater were I hold it inside the cabin exept on the floor close to the seat braket I get alittle movement but not acurate  by all means.  Thanks for your reply.

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Permalink Reply by Bob Pustell on August 15, 2012 at 9:44pm

By any chance did you do any arc welding on your steel tube structure? I know that tube and rag airplanes sometimes drive their magnetic compass crazy and the cause is magnetized steel tubes. Supposedly, it is caused by arc (or most other forms of electric) welding -- not always, but it can happen. The 701 and 750 both have a section of welded steel tube in the cabin structure, the steel could be magnetized.

 

For a tube and rag plane, there is a process of wrapping the tube structure in a wire spiral and passing a controlled current through to de-gauss the structure. Maybe you are in the same need. Come to think of it, you say the compass is best down at the floor near the seat base. That would be the furthest from those welded steel tube areas of the upper forward cabin structure. Does the compass go nuts if you approach the cabin from the outside, say from outside the windshield? How close do you need to get before it goes crazy? Maybe you can use the compass behavior to help locate the source of the magnetic disturbance.

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Permalink Reply by Luzius Thoeny on August 17, 2012 at 9:22am

Hi Bob,no i did not do any welding onthe tube frame,i checked and do have magnetic field on all steel parts . the plan now is to demagnatise some of it.  thanks for advice.

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Permalink Reply by Don Herbel on August 15, 2012 at 9:52pm

Hi Luzius, I have the same problem.  My tech counselor (also a DAR) and an engineer for NORDAM says the welding process for the steel cabin frame magnetizes the tubing and causes the mag compass to go wacko.  The fix is to pass a tool called a de-gauser (not sure of the spelling) over the tubing to demagnetize it.  It is essentially a coil with AC current passed through it.  He says he has used it successfully.  I'm going to borrow his, not sure where you can obtain one.

Don Herbel

CH701 N848DH

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Permalink Reply by Luzius Thoeny on August 17, 2012 at 9:14am

 Hi Don, thanks for the comeback, iwill try to demagnatise the frame system makes sense.

Thanks to all other replys too.

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Permalink Reply by Luzius Thoeny on August 21, 2012 at 8:16am

Hi Don, just an update on my wacky compass.  A friend of mine had a demagnatizer from his old Real to Real taperecorder its alittle handhold looks like a little curling iron, anyway i went along all the iron parts very slowly and real close cant  make contact with it, you can feel a buzz as you go along.  I was actualy surprised it did  work,so   now my compass works real acurate.   I now have my airworthness inspection  set up for  Sep 4th.

Thanks for your info

Luzius Thoeny  N58LT

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Permalink Reply by Bob McDonald on August 16, 2012 at 7:37am

Luzius

By the statement "Does not work in cabin" do you mean it is not accurate to N/S/E/W heading or it does not move when the airframe is rotated. Once installed you have to calibrate (adjust) the compass to a known heading. There is a small brass screw driver for this purpose with the compass. Never use a steel screw driver or force the adjustment past the stops (read manual).

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Permalink Reply by Luzius Thoeny on August 17, 2012 at 9:17am

HI Bob, iknow about the ajustment but it does not work at all points north no mater howe we turn the plane.

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Permalink Reply by Dan Dempsey on August 17, 2012 at 5:01pm

I'm using a Falcon Vertical Card compass in my zodiac, seems to work fine (at least on the ground).  I took great pains to keep it as far as possible from ferous materials.

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Permalink Reply by Shay King on August 21, 2012 at 10:03am

Luzius,

I had to de-gauss the tubular frame around the windshield on my 701 a few years ago. It took about 5 minutes to do with a borrowed de-gausser. Compass is mounted under the windscreen crossmember and has been accurate ever since.

Shay.

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