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More work on the left fuel tank

I’ve been away on holidays which included some time in Singapore. I had the opportunity to check out the new 737-800 flight simulator there called Flight Experience located near the Singpore Flier ferris wheel. I did a take off from Macau, a touch and go at the new Hong Kong airport, and a full stop landing at the infamous, old Hong Kong airport. I also did a night flight around San Francisco Bay, taking off from Oakland and overflying the Golden Gate Bridge. Awesome!

Now that I’m back, I managed to get back to the shed today. Reviewing the plans I found where I had left off and determined that I needed to drill the spar attach holes on the left fuel tank. I drilled these with my hand drill.

The plans then called for the tank to be disassembled (for the last time thank goodness!). So I took it out of the tank holder, removed the clecoes and laid out each piece onto one of my benches. I removed all vinyl and ensure each piece was marked with a Sharpie so I could return each piece to its correct position.

I then got the reinforcing angles that I had marked out last time and put them in the vice. Using a set of files, I removed the excess metal and filed them to the marked lines. I found that using a round file to start in the curve near the base worked well, and allowed for the straight sections to be filed without any risk of cutting into the base of the angle.

A couple of sore arms later, I had both angles filed to the required shape on one web.

The plans then called for the other web on each angle to be marked out to match the profile of the nose rib and cut to shape. As the right fuel tank was partially assembled on the wing, I decided to just work on the left angle for this point on. I grabbed the inner rib and held the angle to the leading edge and traced a dashed line using the rib as a template.

I then set the rib aside and filled in the line free hand to try and have a nice curve, as per the drawing. Holding the angle in the vice between blocks of wood, I cut most of the excess metal away using a hacksaw. I then filed down the rest to the line and checked to see how it fitted.

I filed and checked 3 or 4 times before I was happy with how it fit. I also had to put a reasonable curved chamfer on the corner that rests up into the rib flange/web bend. This allowed the angle to sit as close to the leading edge of the rib as possible and maximise support. Here’s how it looked eventually.

Next I had to drill some holes into the web that rests against the rib however neither the instructions nor the plans offered any measurements to specify where these holes were meant to be drilled. I ended up using the drawing as a guide. The diagram is 50% scale so I used that to mark out the hole locations as best I could. I then punched each hole and drilled them to size on the drill press. I also broke all the edges on my Scotchbrite wheel and deburred on the drill holes.

I then picked out the reinforcing plate, removed the vinyl and cleaned up its edges. Using a clamp, I held the angle and the reinforcing plate on either side of the rib in their required positions. Using the holes on the angle as a guide, I match drilled the rib and reinforcing plate. I put a cleco in each hole as I drilled to avoid the pieces moving and possibly making the holes go out of alignment.

I deburred the newly drilled holes then checked to see what was next on the plans. Looks like I’m up to cutting out that big hole out of the inner rib for the fuel sender assembly. I don’t have a fly cutter so I’ll have to figure out how I’m going to do this, so I decided to call it a day at this point.

Build time 5 hours.


About gstrack

Husband and father of 2. Control & Instrumentation Engineer. Flying nut. Gadget geek.


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