With the majority of the Spider Lug concerns addressed, it is time to start working on the remaining components. The hardware I acquired thus far was focused almost entirely on the attachment of the spider arms/lugs to the predrilled holes for the engine mount in the 4 corners of the firewall. The hardware I purchased for this part of project was an assortment of bolts, nuts, and, and washers. Here is a pic of this batch of AN hardware that I ordered. I could not decide if the length of the bolts that I needed was AN3-26A or AN3-27A, so I ordered about 10 of each so I could check the fit and decide which one to use. The difficulty with this was determining the actual length of the threads for each bolt. AN or MS bolts length (total length) is defined pretty clearly in numerous charts that are found on line, but the length of the bolt shank and the length of the screw threads was not so clearly defined.
To make matters worse, there is yet another hardware identification in use called NAS. So to figure this stuff out you need to be able to cross reference AN, MS, and NAS hardware specifications. I checked various books that I have acquired, including AN43.13, and found them seriously lacking in details about the hardware, so I had to resort to other on line sources. There is good info in Aircraft Spruce and Specialty website (search for AN Bolt Selector)< and also on various website via google search, as well as Aircraft Genuine Hardware's website, and even from links and info found on VAF.
From that research I was able to find out that most AN bolt hardware contains threads that are approximately 1/2 inch in length. but in reality the spec is to create threads to allow for at least one or more washers to be applied, then apply an appropriate nut, and still have at least 2 threads showing after the nut is properly torqued.
What I found was that, although the AN3-26A seemed to allow threads to appear where the bolt exists the hole in the firewall/engine mount steel support bracket assembly, the slightly longer AN3-27A bolt shows a small amount of shank that a washer will cover nicely before the nut is applied, so I think I am going to go with that.
The hardware in the above pic was obtained from a local source - an maintenance facility at Centennial airport (KAPA) called Straight Flight. They offer certain hardware and other items for sell to folks like me. I was first made aware of them from a post I stumbled into a few years ago regarding some problems with Nut slippage and bolt thread issues with the Bolt/Nut combination that Vans provides for their RV-8 Landing Gear. Apparently the Nuts would lose their grip, causing the bolts to become loose - not a good thing. So a discussion ensued and someone ended up recommending a different NUT that seems to work much better and resolves this slippage problem.
Somebody local ended up posting that they found the new hardware from Straight Flight and were able to pick it up without having to have it shipped from somewhere else. that supplier was Straight Flight. So that is where I purchased the hardware you see in the pic, except for the 3/16 x 1 inch stainless flat washers in the noticeably orange packets that came from HD. Very nice to have a local aircraft hardware vendor located not very far away from me.
I purchased AN360-10 and AN360-10L washers (thick and thin versions) and standard and lock nuts so I could decide which of those I anted to use in the final assembly. Then next thing I had to purchase is the steel angle for the arm extensions between the bracket and the Spider arms. I purchased it from HD and got 2 48 inch long 1x1 inch pieces of steel angle:
These will be cut to size once I determine the lengths that I will need for all 4 arms. I also ordered some other hardware that I am waiting on from Aircraft Spruce for this part of the assembly. Straight Flight did not seem to have the sizes I was looking for, so I had to order them from Spruce. More on that in the next post.
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