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Upper Cowl Hinge Play

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skelrad

Well Known Member
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I thought my cowl was fitting pretty well and I was getting ready to rivet hinges and clean up a few edges, but I just realized that when everything is on, the upper cowl pops up above the fuselage skin quite badly. With the smaller diameter hinge pin in place, the hinges have enough slop that I can easily move the top line up and down, even though the side hinges are held solid.

Any recommendations on how to remedy this?
 
What are you building? I built a -4, and it pulls down pretty well when both upper and lower cowls are fitted. Its a trick getting them all to fit. Attach pics for better response. Depending in how deep in to the cut and fit you are, you may need to take some drastic measures.
 
fixnflyguy said:
What are you building? I built a -4, and it pulls down pretty well when both upper and lower cowls are fitted. Its a trick getting them all to fit. Attach pics for better response. Depending in how deep in to the cut and fit you are, you may need to take some drastic measures.
Click to expand...
RV9A - standard hinge setup. The cowl fits fine except that when the sides of the top cowl are attached at the horizontal hinges, it puts just enough pressure on the middle of the top cowl to have it bulge upwards a little. It takes very little finger pressure to move it back down, so it's not under a great deal of stress or anything. The issue is the slop that exists due to the smaller hinge pin Van's specifies to allow the pin to make the curve downwards at the outside portion of the cowl. I may just have to try to upsize the pin diameter to remove some of the slop.
 
The hinge attachment is fine for the top and bottom halves, and the aft bottom sides (maybe) -- it's a really cheap, light weight solution thats time came & went in 1983.

Consider using screws instead -- A couple of pieces of 0.040", and 0.025" shim stock, AN426AD3-4 or 1097-4 rivets, K1000-08 plate nuts, AN507C-8R8 with 3600F counter sunk finish washers. ~2 - 3" spacing for the screws.

No fretting over lining up the hinge "eyes", no broken hinge eyes after ~500 hours, etc.

Plus you'll go faster (apparent airspeed).
 
If your not painted yet, you could drill the hinge off the aiplane side 6-10 inches either side of centerline and shim it downward to compensate. Make it a tapered shim so it blends back in where the protrusion stops.
 
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