Prop Governor - Magnetized

I have a bit of an odd one for the crowd and hope to get some thoughts. Superior IO360 with 1650 hours, Whirlwind RV200 CS prop and Jijastraj P-940-028 governor with same 1650 hours (installed 2009 with new engine).

My problem has been surging when doing touch and go's at full power and high RPM (2700). On first takeoff of the day, there is no issue whatsoever and no surging during climb. Once the engine is at normal operating temperature, I get surging at high RPM and full power but can make it stop by pulling back to 2550 or so RPM.

I figured it must be the governor so I sent it into a respected governor shop. They put it on the bench and were able to re-create my surging at top RPM (30-40 rpm surging).

Disassembled and did an overhaul. Parts were all fine no issues uncovered such as parts being out of spec. They did uncover that every part in the governor was materially magnetized. They believe this was responsible for the surging or hunting at highest RPM.

They de-magnetized every part of the unit, put it on the bench, and no surging any longer.

My question is has anybody ever heard of this and more importantly, any idea how this governor could have become so materially magnetized? Do I have a grounding issue or electrical problem? Everything on the plane works perfectly after 1650 hours and I was definitely not expecting this to be the culprit. Any thoughts would be much appreciated!

Pretty wild
Ground cable attached to Gov mounting stud?
Inadequate grounding causing current to flow thru the Gov cable/gov.?

Thanks Walt. I am going to check my grounding as I don’t remember looking to see how they did it but any best practices I should be looking at by chance? Grounding seems pretty straight forward to me but it’s those seemingly straightforward things that can get me in trouble.

Rare finding . . .

Wow, that is a new one. Makes one wonder about other components. Have you waved a small compass around in the FWF? Kudos for the shop, I wonder how they knew to look.

Bad engine ground ( check fastener torque) , lightening, arc flash to battery?? Puzzling.

Assuming it would take some amps to do that, then related to starting. In that case: ground. So if the cause remains, and if its a ground, then checking fasteners, tugging on the cables, and finally a voltage check from the engine to battery post during starting should reveal something.

I guess with some things one just has to move on and keep the antenna open for a signal. I have collected a few of these things over 6 decades and the answer has popped up. Usually, the question has been long forgotten, but is recalled when the answer appears.

Did you know our sun will enlarge and fry us some day? I am so worried about that.

Magnetized Parts

Someone probably performed a Magnetic Particle inspection on the hub looking for cracks and did not demagnetize the parts afterward. I have seen this on many part that have been inspected this way. You can usually detect the magnetization using a simple hand compass.

Well, havent been this frustrated in a long time. First flight after getting the prop governor overhauled and I had 30-50 RPM intermittent surging at full power during climb on takeoff again today.

I just dont know where to look at this point other than could it be the Phillips 20w-50 is just too thin for this Jijastraj and Whirlwind 200 combo and need to go to Aero 100? I just dont know what else it could be or where else to look... after spending $1000 overhauling the governor which probably didnt need it, I could use any guidance on next steps. My A&P thinks I need to change to Aero 100 but that is all he can think of at this point.

Thanks for any thoughts or guidance!

Frustrating

Can you pull logs to look at all the available engine parameters? Fuel flow, fuel pressure, MAP, anything that might marry up to the RPM fluctuation?

Aero shell 100w+

I had a problem where the prop wouldn’t hold rpm, I called Byam Propeller, he told me to switch to aero shell 100w+ (whatever variation of 100w you prefer), and that he had at least 3 other customers with the same problem where that fixed it. I switched mine and have not had any problems since (about 70 hours since). So it’s worth a try and cheaper than other proposals.

Thought about something and wanted to see if there were any thoughts. On the Whirlwind site, they say the relief pressure needs to be in the high 400's which is pretty high for prop governors. I guess it is due to this specific prop RV200.

Would relief pressure being too low be a cause of this surging issue? I have also heard about a bearing or seal in the engine and to do a differential pressure test on the case?

Still searching on this one.