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Dave's Sonex Builders Log

Welcome to my builders log for Sonex S/N 767. It won't be as big as a real 767 but if you scale the speed I bet it will be almost as fast.

This website is to log my progress while building a Sonex airplane. I purchased the plans for Sonex S/N 767 and began construction around Christmas 2004. I would like to keep my costs down and am currently considering the AeroVee engine. I'm also building the Sonex with standard gear and a single centre stick.

Third times a charm?! I was still not happy with the fuel line routing/bending so I decided to try once more. I was very careful to avoid any uphill bends under the fuel tank. While the line runs downward on an angle when the fuselage is level, the line will move more towards the horizontal when the plane is in a steep climb. I had to put a slight upward bend in the portion under the tank but for the most part the joggle bend is horizontal. Forward of the firewall the line runs only down hill. This time I'm pretty happy with the outcome. 

I also notched the bracket for the gascolator so that the gascolator could be removed without removing the bracket once the fitting was installed. I installed the plug in the gascolator but I still need to use some lock wire on them and the cotter pin the fasteners.

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I worked on finishing the gascolator end of the fuel line. I started by shortening the line until it was the appropriate length to flare. Next I flared the line an checked the fit up. I'm not too happy with the routing inside the fuselage under the gas tank. I have a short segment that may be uphill when the plane is in a climb. I'd like to eliminate this if possible.

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Today I went back to work on the firewall installing the bracket for the gascolator. There has been much talk about not using this but I'm going to give it a try along with insulating the fuel line so that I don't get vapours causing hick-ups.

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I started on the left gear leg engine mount attachment point. I needed a thin washer and a thick washer to get the hole in the bolt to line up correctly with the castle nut when torqued properly. I put the thin washer at the head of the bolt which allowed me to put the thick washer at the threaded end. The bolts still end up a bit long and the end of the bolts want to rub the firewall. I ended up putting a large flat washer or "fender washer" over the end of the bolt to provide a large bearing surface against fire wall. I saw this on another Sonex and it looks like it works. The cotter pin does not seem long enough. I'm planning to order some additional cotter pins that are longer for this bolts. I'm not sure why, but the Sonex specified cotter pin is a 5/16 inch diameter but the standard cotter pin for the AN4 bolt is only 1/8 inch diameter which would fit nicer. I'd also like a longer cotter pin since I need to wrap the legs around the nut instead of over the top.  When putting the cotter pin in 90 degrees to the bolt it does not go into the castle nut as far as I would like.

I also installed, torqued and cotter pinned the fasteners in the lower end of the main gear legs for the front axles.  This was easy but I needed two thick and two thin washers. I considered using a shorter bolt but I was not happy with how far the bolt came through the axle mount. I used the longer bolt so that the shank of the bolt was fully engaged in the mount to minimize the  possibility of the holes becoming oval over time.

I went back to the wheels. Previously, I had assembled one of the wheels and found that the valve stem ended up very crocked. I wasn't happy with the assembly. This time I made sure the valve stem was through the hole in the rim with the rubber resting against the rim. This time when I inflated the tire to 30 psi the stem remained straight. With one wheel assembled I proceeded to the second wheel. The bolts holding the wheels together are 5/16 inch diameter so I torqued them up to 85 in-lbs per the Standard Aircraft Handbook. I made sure my compressor was set to a max of 30 psi since this is the limit stamped on the side of the rim.

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Today I worked on the landing gear some more. I wanted to install the 1/4 inch bolts to secure the main gear.  I discovered the upper bolts specified were long enough but I needed a thin washer to get the hole in the castle nut to line up properly.  I also need to get some fender washers for on the end of the bolt to spread the load from the end of the bolt over a larger area of the firewall. The shorter bolts to secure the axle stubs in place were way too long. I ended up ordering shorter bolts for these. I am using the disc brake setup from Sonex so it makes sense since I won't be installing the cable deflector for the mechanical brakes. I worked at assembling one of the wheels. Once I put air the tube moved and I don't like the position of the stem. I'm going to have to deflate these and reposition the tube.

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I still need a number of parts to complete the landing gear. I reviewed the Sonex revisions list and prepared an order for Aircraft spruce of the hardware, wheels, tires and tubes. I'll probably upgrade the tires later but I need something for now to get the fuselage on the ground.