Building C-140 Patroller Doors

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Building C-140 Patroller doors

Patroller doors are one of those things that look really cool but are pretty hard to find. A number of people have modified regular cessna doors to make them, and this is my attempt at that.

Standard C140 door

This is the starting point. I marked out the cutout based on dimensions taken from the cessna drawings and then used a cutoff wheel to cut it out. Go slow, this will leave a nice cut that requires minimal effort to finish later. I left the corners like that so they can be rounded out nicely later on.

Outside skin cut

There's the outside skin cut. Had to drill out a few rivets to get that free from the inside skin.

Inside skin cut

Working on the inside. Notice how it's pressed outwards - that's for rigidity, but will make this modification a little more trouble because we need that to be flat now. Next step is to separate the door skins. This means drilling out a lot of 3/32 rivets. I used a 3/32 bit, drilled the head "just enough" and then used a pin punch to drive the rivet out the back. It goes quicker than you would think.

Relief cuts

This was my solution to getting the pressed inner skin to lie flat, making a number of relief cuts.

Inner doubler

My door had some cracks by the latch so I made a doubler to go inside this area. Hindsight: putting this on the outside instead of inside would have done the same thing I think and looked nicer. Next step is fabricating the 'Z' channel stiffeners. I didn't find a place to buy this stuff, it's kind of a specific dimension... so I made it on a sheet metal brake.

Laying out for bending

I did some trials on little pieces of metal to set the brake up for the the desired dimensions/bend radius. Saved those dimensions and then laid out on the large aluminum sheet...

Finished Z channel

Turned out OK. This brake(and operator) is not that great and they are not perfect, but they're straight and within 1/16" or so of the dimensions on the cessna drawings.

Door handle hole

The door handle leaves a hole where you don't want it.

Door handle patch

I made a small patch and flush riveted it in place...

Clean outside skin

Stripped off all the old paint. There was quite a bit of it, I think this had been painted more than once.

First stiffener

Now, start attaching the stiffeners to the outside skin. I basically lined them up so the edge of the stiffener matches the cutout. Holes are drilled according to the cessna drawings...

First stiffener view 2

Another view of that.

More stiffeners

Continuing around...

All stiffeners

All of them in place! I basically cut them all to the lengths shown in the cessna drawings and they fit well.

Test fit

Next I put the skins together and here's how it looks.

drilling holes...

Then, use a bunch of clecos to hold the skins in precise alignment. I think this is critical to making sure it all goes together well when we start driving rivets. Once the skins were aligned, I started drilling holes through the other side of the stiffeners and inside skin.