SD8 issue

GaryK · #1 07-19-2009, 11:34 AM

I think my SD8 is broken. It's not supposed to rotate freely with the engine not running, it does. Is this something we can fix ourselves or does it need to go back to B&C.

Thanks,

Gary
RV7A 600+ hours
N715AB

vic syracuse · #2 07-19-2009, 11:45 AM

No it doesn't have to go back. There is a nylon spline drive that connects it to the accessory drive. It is replaceable. B&C has them. Just call them, as I don't see it on their website. It's a quick repair. Just take the SD-8 off, pull out the broken one, and replace it. These work the same way the vacuum pumps do. They are designed to fail and not hurt the engine.
Now, you might want to figure out why it broke. It might just be age. They had some weak drive splines a few years back, and changed them. I had a failure with the weak ones, but haven't had a failure with the new ones on 2 SD-8's now.

Vic

GaryK · #3 07-19-2009, 08:26 PM

Thanks Vic,
Here is a picture of the broken plastic behind the spline. I'll call them in the morning.

http://img263.imageshack.us/i/sd8.jpg/]

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BillFear · #4 02-18-2012, 03:26 PM

My SD8 is not working and after learning it is supposed to spin when the engine turns, we checked and it is not. You can grab it and turn it, it is not totally free, feels like magnetic resistance as you turn it. Does this sound like the spline issue?

Thanks for any advice you can provide.

Walt · #5 02-18-2012, 03:36 PM

Yep, same issue as above.

BillFear · #6 02-21-2012, 03:50 PM

Have the very expensive plastic coupler piece on the way from B&C. They seem to have very good technical support and have been very helpful as I tried to troubleshoot the SD8 and its wiring.

Appreciate the VAF help as always!

BillFear · #7 02-28-2012, 04:03 PM

Had to buy the sheer coupling and the spline piece from B&C. Put it back together and tested last night. Was delighted to see that the little SD8 can power the whole panel as long as the lights/pitot heat are off. Its also great to be able to start the engine with the EIS and the GRT Efis units up and running off the back-up battery.

Very happy camper.

molson309 · #8 02-28-2012, 05:24 PM

I had one go bad on the SD-8 in my RV-7A. The color of the one that went bad was white and the replacement one was green. Apparently the white one is an older design and prone to failure. Mine went out at about 200 hours. The plane now has about 700 hours on it and the SD-8 is still going strong.