I have had the Dynon 60 amp shunt break around the mounting holes twice in 330 hours. It is attached to the fire wall high on the right of my RV10. I was especially careful about mounting it the second time to make sure there was no extra pressure on it. This time I got a friend with an end mill to make me a replacement part to mount the metal part on out of Delrin. It is a solid piece with holes in all the right places to mount the metal piece and properly countersunk. Hopefully this is the last time I have to fix it. It sure is mounted much more solidly than the hard plastic piece it used to be mounted on.
Shunt breakage
- Thread starter rjones560
- Start date
Did you (or anyone out there) have any better installation instructions using the existing base? Mine has cracked too and I see from the internet others have had a similar issue just trying to get the thing installed. Any suggestions would help. Thanks.
airguy
Well-Known Member
Wow, I've got a pair of them in my airplane with more than 1200 hours and not a single crack - what are you guys doing to them?
Rhino
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Or maybe a better question is where are you mounting them? You might be better off with a location that isn't as subject to vibration. You can also add some vibration dampening material between the base and whatever you're mounting it to. Might want to avoid the hottest locations too.
I had mine on the engine side of the firewall. Inside the cabin was a non starter because I have 2 alternators wired to one side of the shunt and I was not going to put 2 passthroughs for power through the firewall. I was very careful not to screw the shunt down tightly so that I would not put put any extra stress on it. The housing is just to brittle to take any vibration at all. It way as well be made of glass. The base I have now was machined to fit the metal part of the Dynon shunt out of a piece of Delrin. It it plenty tough enough without being brittle. It us far more satisfactory
Sorry, misunderstood that.
airguy
Well-Known Member
Hah! So I was mouthing off about how I've got so much time on my shunt without breakage, and wondering what you guys were doing to them... then I started my annual inspection this week (RV9A), and guess what I found? Yup, I just ordered a shunt... 7 years and 1250 hours, but it finally gave up.
I think the housing is pretty brittle. I permanently fixed mine by milling out a new housing out of Delrin. Certainly where it is mounted will make a lot of difference in service life. Mine has two #6 cables hooked to one side, one for each of my alternators and the shunt is mounted high and to the right on the firewall.
swatson999
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Is that lower wire temporary? Stripping a wire and wrapping it around a screw is not an acceptable method of connection. It needs a ring terminal. But then, seeing as how it's you, Vern...you knew that
.For what it is worth, I am based in Las Vegas and I fly with ambient temperatures over 100F and I have seen no sign of a problem with my Delrin base for my shunt. Phenolic material will take higher temperatures, but that does not seem to matter.
Rhino
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It may be more installation based than local environment based. vlittle had one melt, making it an issue in at least some instances. You're probably right that it would be a rare occurrence. But it's possible, so I offered that in case anyone had that concern.
Marc_J._Zeitlin
Active Member
Not just "frowned upon".
No solid wire allowed per good manufacturing practices. AC 43.13-1B, Chapter 11, page 11-21, section 11-66(a) is clear that no wire with less than 19 strands shall be used. 1 < 19, last I checked. Not regulatory, but...
Rhino
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Thought so. Thanks.
