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So Mike Reagan showed me a few weeks ago how he installs his side cowl hinge pins from the inside. Tonight was my attempt to copy it with some improvements. I bought some 3/16" aluminum tubing to act as a guide for the cowl hinge pin. The idea is to run it from the F-902 bulkhead to the firewall, and have it penetrate the firewall right where the top hinge pin lines up on the side.  I already had a pilot hole on the firewall, so I enlarged it to 7/32" -- 3/16" would of been too tight and chaffed the soft aluminum tubing.  Next I worked on the F-902 bulkhead. I wanted the tube to go through the F-902 and be secured to it with an adel clamp from the inside. So, I took a TON of measurements, since I need to weave around the fuel vent tubing. These are the holes I came up with. The 3/8" hole on the front is for the tubing, and the #12 hole on the inboard side is for a screw to hold the adel clamp.  The adel clamp on the inside needed a spacer from the inboard edge of the F-902 bulkhead. I made this out of 3/16" bar, and countersunk it for a #12 dimple.  Here is the idea of how it all goes together. The thin sheet on the left represents the F-902 bulkhead. The spacer not only offsets the adel clamp outboard, but it also takes care of adapting a dimpled surface to a non-dimpled surface.  So here it is all together with the hinge pin ran through it.  This is the forward side. The tube lines up pretty well with the hinges on the lower cowl.  Here is the trick -- you want the eyelet on the lower cowl to be the closest one to the firewall (as opposed to the eyelet on the top half being the closest). This is because the tube and the eyelet don't line up 100%. You need to get it started in that first eyelet with your hand. Once its in that eyelet, you can put the top cowl on and your day is pretty much done.  So I can't have these ugly hinge pins in the fuselage without some class on it right? I bought some knobs from the hardware store. I tapped what I could in them to 4-40.  I also threaded the hinge pin to 4-40.  Then I screwed them together. The knob is pretty hollow, so I am going to epoxy these together later on for more strength.  Here is is slid in with the knob on. Looks awesome! Works awesome! Before I can put this in permanently, I need to install the brakes and the vent lines. 
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Last Modified: October 5, 2024 |