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More Firewall Work

January 10, 2013

The first real building tasks on the fuselage is the firewall.  As the name implies it is the physical barrier between the engine compartment and the cabin.  It is made of stainless steel and it supports and transfers the weight of the engine to the rest of the frame of the aircraft.  The firewall is the largest stainless steel structure on the plane.  Not having worked with it before there is a bit of a learning curve.  It is WAY harder than aluminum and needs some special attention when drilling.

Firewall parts ready to be assembled.

Firewall parts ready to be assembled.

I got all the parts that were needed into a pile so I could see what I was working with.  Lots of edge prep, drilling and dimpling is needed.  First thing to do is layout everything where it is going to go, label it and see what needs to be done.

Fuse - Firewall - Dry fit

Here are the firewall components cleco'd in place and ready for drilling.

Here are the firewall components cleco’d in place and ready for drilling.

There are several parts that have to be fabricated before you can assemble.  These are all pretty easy.  There are two doubler plates and two brackets.  The brackets are in the picture above on the left…triangles with one tip cut off.  These were a bit of a pain to get situated.  I was not really able to achieve the 3/32″ separation between the bracket and the bottom edge of the firewall.  I got pretty close, but every time I clamped it down it would move just a smidge.

Fuse - Drilling in oil

Blast!  Adam found the camera.

Blast! Adam found the camera.

Detail of the aux fuel pump doubler.

Detail of the aux fuel pump doubler.

Fuse - support bracketDrilling the stainless you have to lubricate and go pretty slow.  That is why I am using the electric drill.  The oil you see above is for keeping the drill and the work cool.  I found out, through trial and error, that there is such a thing as too much oil.  I found that if I used a small amount of oil at a time, the hole drilled much quicker.  Many of the holes in the firewall are just being match drilled, but there are enough that need to be drilled that you have to pay attention to this.

It is mostly cut, fitted, de-burred and drilled at this point.  I still need to dimple and countersink all the holes that need it…which is most of them.

Another thing I did was get a lot of priming done.   This is a bit of a departure for me…I dont usually do priming until it is ready to assemble, so I’m curious to see what the results will be like dimpling primed metal.

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From → Fuselage

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