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just install a degaussing ring around your airplane.

One of the main problems (but certainly not the only one) that can affect the compass are the inductive components in the DC power supplies. DC magnetic fields (or net DC fields) are not effectively shielded by metal boxes or other shields (they're intended for rf shielding). It doesn't take a ton of current for a few unfortunately located devices to generate sufficient field to affect a nearby compass. The good news is that moderate spacing helps mitigate this when it's a problem, so the usual practice of putting the compass a little bit higher than the panel electronics is generally sufficient. The center steel support in a J model used to mount the compass is stainless steel, so non-magnetic and should not affect the compass. Some older Mooneys had a plain steel support there that might require occasional degaussing. The cage components around the rest of the cabin and panel are steel, and susceptible to magnetization. In-panel compasses aren't that unusual and can certainly be made to work, it's just not always a slam-dunk and the magnetic environment can change and be more dependent on nearby surrounding device behavior than elsewhere sometimes.

Hi all, I'm currently getting new insulation installed in my '78 J. The shop doing it is concerned if they use the aluminum-backed insulation, they'll need to degauss afterward which in the past they've found to be time consuming. Just wondered what experience others have with this? Is degaussing typically part of the process when you carry out SB208? Or do others use another type of insulation without aluminum? Thanks, Matt

really good technical question!!! Bringing electric motors inside the cabin is my favorite way to magnetize my steel tube frame…. Nothing like being the king of degaussers… without a magnetic compass that won’t work… now the question is…. How small of a motor can I get away with… or which vac is fully shrouded from mag waves…? leave the vAc outside, bring in the long hose…. PP thoughts only, degaussing properly is a big pain… best regards, -a-

A couple of ways to attack this challenge… Airpath is the standard compass maker found in most Mooneys… Aircraft spruce carries all the parts needed for OH, or just filling, including new seals and a fresh compass calibration card… or a complete swap for new… for a pre-flown replacement direct from an actual Mooney… contact Alan…. At Mooney Parts R Us… @Alan Fox there are better compasses available…. there is also a reason why you may be asking about fixing the old compass… when the problem is not the compass itself… this is called degaussing…. there is a nice steel tube frame that can get accidentally magnetized… When this occurs, the compass can slow/stall during standard rate turns…. Then accelerate to catch up… making partial panel under the hood exercises impossible to accomplish… For degaussing the airframe… there are plenty of discussions around here somewhere…. its not a common occurrence… unless you bring a giant vacuum cleaner with a big electric motor inside the cabin…. modern Mooneys actually got a SS tube down the center, where the older Mooneys got a more magnetic sensitive steel… PP thoughts only… my first attempt at training for the IR went on hold for this reason… Best regards, -a-

Will degaussing hurt anything? This is a tough question since it is impossible to imagine every conceivable system arrangement that could be subjected to degaussing. In all our experience we have never had any electronics device hurt by the degaussing process. This is because the induced voltages from the degausser are low, and the electronics components have a fairly high impedance at low voltages. It would be safer to degauss electronics while the power to the electronics is turned off in case the small induced voltages cause the device to operate incorrectly. It is always safe to degauss any of Geometrics’ manufactured equipment (including the sensor). On the other hand, here are some things to consider when degaussing some types of objects. Large conductive planes or rings will have large circulating currents induced in them by the degausser (but the voltages are still very small). This induced current will produce an opposing magnetic field that will fight the degaussing field – causing both the degausser and the conductive plane/loop to vibrate substantially. If the device being degaussed is sensitive to this vibration (intricate mechanical workings and the like) then this is a possible route for causing some damage. Also, sometimes objects being degaussed have embedded magnets that are necessary for the device to operate properly. A good example is a device with a permanent magnet speaker inside. Generally it is hard to degauss a magnetically hard permanent magnet, but the degausser is strong enough to at least partially do the job. A partially degaussed speaker (or other object that requires a magnet to work right) isn’t going to work the same as before – so be aware. [Things that have magnets in them shouldn’t be used near magnetometers anyway.] https://www.geometrics.com/support/magnetometer-degaussing/#:~:text=Degaussing misaligns magnetic domains so,are not sufficiently magnetically randomized. While the degausser may demagnetize the compass needle, I don't see how it would hurt the modern solid state magnetometer. They use hall effect devices, which are not magnetized and should dutifully measure the fields from the degausser without damage.

Putting in proper insulation can’t possibly require degaussing an airframe… Unless the shop intends to bring the industrial vacuum cleaner into the cockpit to clean up after the work… Large electric motors have been known to magnetize things nearby…. If you have done compass turns… and there is a heading that the compass hangs on….rests a moment… then accelerates to catch up… this is a sign of a magnetized cage… PP thoughts only, not a mechanic… Best regards, -a-

Why would they think degaussing would be necessary? Tell them not to use electric tools when they put it in.

MMs, You are bumping into an area that is kind of unique… you might want to clear up why you are training for the IR… what is it YOU want? Because, the young guns heading towards their ATP might be thinking you are on their same path…. If you are more like I was… ADF, VOR and ILS was all I had…. My first IR training went on hold because there was no MS, and even crummy insight was hard to find… Honest quick discussion with potential CFIIs… “Can I earn my IR, with this panel, with you as my CFII?” Great honest question… My biggest problem was my compass was having difficulty with a magnetized roll cage… MS has answers for that as well… degaussing… As far as DME goes… it wasn’t the most popular device in the panel for most GA planes… and has been replaced by GPS distance for the most part… nice to have… now or after you have the IR… Have two independent ways to get to the ground…. What was once called precision approaches… The ILS will do it… a WAAS GPS approach will do it… This is a safety issue… descend to within 200’ AGL to find the bottom of the clouds before landing… You will be spending a fair amount of time over the clouds… and many miles of clouds you fly over can get close to the ground… and stay there a long time… You may need to descend through them for a landing… Expect your favorite nav box to go dark one day… So have a good plan B for that… Briefly… many modern GPS navigators, also have VOR, and ILS, in their same box… like a G430W(aas) +1 for second AI… because the TC has proven to be disappointing too often… Being able to fly in the system is a great safety enhancement… PP thoughts only, not a CFII… Best regards, -a-

Many Mooneys got the panel mount one… Airpath shows many options that I didn’t ever know about… and options for the times the calibration isn’t strong enough… There are also degaussing conversations around here for the times your steel cage gets over magnetized… -a-

Read from top to bottom… The thread became a discussion of magnetization and degaussing… resulting in no harm no foul… and methods of knowing… -a-

Does this pose a risk of magnetizing the steel roll cage ? We occasionally see a thread about degaussing and I wonder is this how the roll cage gets magnetized ?

There is a lot of pre-heat options discussed around here… including remote operation using the latest cell phone switch options… Use caution with big electric motors inside the plane… you can accidentally magnetize the steel cage…. Degaussing it can be really hard… The magnetic compass can hang up on certain headings, if you ever have to execute compass based turns in simulated IMC…. Find @OSUAV8TER he is our remote heat supplier…. Has an excellent engineer supporting his product… who can supply this detail… Best regards, -a-

Before I knew what a magnometer was, I had a love/hate relationship with my magnetic compass. I am convinced after degaussing my plane a few times that most of the time when a magnetic compass has become “magnetized” it is caused by power leads being tie wrapped to the roll cage. Thank goodness for balancing balls. [emoji6] Sent from my iPhone using Tapatalk Pro

Although support from the folks at Uavionix have been exemplary, it looks I will be pulling both AV30’s from my panel due to a dead end in solving a “lazy” AI issue. I still like the company a lot and have nothing but great things to say about the engineer there who has been patiently working with me since the original install. She went above and beyond in terms of time spent on the problems. In the end, I do not feel comfortable flying into actual IMC with the units and I can’t justify a pretty day Mooney. Actually, probably can’t justify the airplane regardless but that’s another subject entirely. Looking at replacement options now and am leaning toward the latest version of the E5. I have been unable to find good opinions online of the basic version and how it performs when in the weather. Does anyone have or know of anyone who has installed the unit with its HSI and can share flying experience? Also would like to check out an install in person if possible, doesn’t have to be a Mooney. My own AV30 issues involved an AI that would still show a mild bank when visually level and level when in a mild bank after a heading change. It was enough that when IMC, increased workload significantly to maintain heading and altitude. DG did end up precessing less, up until back up battery failed and now has to realign every flight. Rectifying attempts included multiple initial set up menu actions, degaussing of airframe, replacement of voltage regulator, dynamic balancing of prop, and more. All pitot static driven functions worked perfectly, internal AHRS, not so much. Appreciate any knowledge about the latest Aspen basic box…

I do have the proper degaussing tool if needed, I thought I said that early on but I may have only thought about it and never sent that out. @DXB, don't attempt to electrocute your self next time I'll meet you at UKT. Brian

It's not a bad idea - a whiskey compass is more likely to be compensated than a vertical card - however that swap didn't work for me, and i still had to go through the ordeal of degaussing. In the end I didn't even get asked to do compass turns on my IFR checkride; had I known I wouldn't hav bothered with the hassle

Degaussing properly should get things working well enough... Avoiding large magnets being brought into the airframe will help things from getting worse again... Leave the big old industrial vacuum cleaner motor far away from the plane... Best regards, -a-

I ordered a CRT TV degaussing coil off eBay today hoping I can demag this thing.

I’ve tried shielding - zero luck. In my case it required degaussing both the front of the steel cage AND the engine mount. And vertical cards are more finicky than whiskey compasses in this regard. Make sure your compass is far away outside the plane when degaussing.

I have a degaussing tool, I have used it on several mooney's including mine when I first got it. it does seem to make a difference on the wet compass but I'm not sure how often it needs to be done. I installed the SIRS compass in my Mooney and haven't had to degauss mine since, not sure if its because I changed out most of my old avionics or the SIRS is less affected. Brian

https://mooneyspace.com/search/?q=Degaussing&quick=1 Have a quick look through these... The key word is degaussing... The growler I believe is the tool for this act... PP thoughts only, not a mechanic ... -a-

The next time you go flying... Try performing a standard rate timed turn... while watching the compass... If something magnetized the airframe... the compass will not behave smoothly... you can watch it stop, then accelerate to catch up... at certain headings, it can get stuck... as it doesn’t have much strength to break through the odd magnetic force... Then, you will be looking for info on degaussing... PP thoughts only, not a mechanic... Best regards, -a-

My avionics guy says that he’s never seen a plane this bad in his 20yrs of doing this...and so isn’t familiar with degaussing a Mooney. I’d do it myself if I had that tool. Lol

Easy to say. Have you read the Mooney procedure? And these degaussing guns...they don’t rent them at Lowes. The balance balls for this compass specifically call out addressing Mooney roll cage mag as a reason to use these balls. Going to give them a try.