[mlwynn]

As I am about to wrap up my build, I discovered a very small brake fluid leak from the upper NPT fitting going into the grove airfoil gear member. After lots of head scratching, I think I am going to have to drop the gear to get to the fitting.

That said, I thought this would be an idea time to change over to the NAS 1804-6 Nuts on the outboard fitting. I currently have the NAS 679A6 sent with the gear from Grove.

Does anyone know if the bolts will be long enough and if I need to change them, what bolts and washers do I need to use? It looks like the washers are key to a safe installation.

The inboard three bolts have the nylon locking nuts that come from Grove (or maybe Van's). Is anyone changing these to the 1804-6 nuts? Any reason to do so?

The Steve Smith, Bob Kuykendall study was really a first rate piece of research. My congratuations to them for their fine work. If I understand correctly, the issues and the study are all focused on the outboard bolts.

Regards,

Michael Wynn
RV 8 Finishing
San Ramon, CA

 

[ColoRv]

Mine came with the early nuts. 1804-6's worked fine. $2.50 each from local maintenance shop. Gahco wanted a kidney as I recall. They are remarkably difficult to find online for some reason. I only changed 4.

 

[NoPlugs]

If you want a stronger nut look at these HS20-6, 220KSI compared to the 180KSI, NAS1804-6. Pegasus racing has them for $6.99 each


http://catalog.alcoafasteners.com/item/wrenchable-nuts/h20-twelve-point-nut-220-000-psi/h20-6

You might want to look at this failure report by NASA, with some nice photos, The testing was to test bolts but they used NAS1805 nut which have the same 180KSI rating but are made of CRES (Stainless Steel). On Page 13 they used H20 nuts.
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20120003667_2012004005.pdf