Saturday 15 December 2007

Fuel Tank and Boot Cowl

It is early December and work is progressing as quickly or as slowly as I had anticipated. The fabric is off except for the area immediately surrounding the doors, instruments and panel are out as are the seat, baggage sling and floor. The next thing I want to tackle is the main fuel tank and boot cowl and for some reason I decided to do it in that order, probably because I imagined that removing the boot cowl would be more difficult than is actually was. In hindsight remove the boot cowl first as this gives you much better access to the nuts that hold the tank in place.

Removing the tank is not difficult in itself, just disconnect all the fuel lines, undo four nuts, remove the mounting rods and hey presto, one tank removed. Of course in practice there is muck skinning of knuckles as you try to reach that inaccessible nut or your spanner slips in a confined space.

The tank is held in place by two threaded rods that pass through the tank and then through short tubes welded to the fuselage tubing. These are locked in place by nuts.
To prevent the tank vibrating, felt is trapped between the rod and the tank (this can be seen in the picture where the rod exits the tank body.
All four nuts are fairly easy to remove allowing the rods to be pulled through the tank body. The tank can then be lifted out from between the fuselage tubing (this would have been easier if the boot cowl had been removed already because I wouldn't have had to maneuver the filler neck through the boot cowl which required a little forceful help on the way).
Note that the tank should also have some felt pieces glued to the side of the tank to prevent it from vibrating against the fuselage tubing.
The boot cowl was then tackled and this turned out to be very easy, just a matter of removing a couple of dozen screws from around the boot cowl and firewall. The boot cowl was then prized off the supporting framework revealing the tubing for the first time in decades.

This revealed the first bit of corrosion on the tubing. It looks like the paint had peeled off the tubing some time ago allowing the steel tube around the engine mount to rust. I have since used an automatic center punch to test the tube and found that it left only a small mark on the tube so I don't think the corrosion is serious although I will leave the final decision to someone with more experience in these matters than myself.



This nows gives me a lot more room to work and I have since removed the 'H' frame, rudder bars, aileron pulley's and cables. These have all been bagged and tagged and put away. Although it looks as though the fuselage is stripped, there is still a lot of work to do. All the stringers need removing along with the elevator/rudder control runs and I need to clean up the tubing so that it can be visually inspected for damage/corrosion etc.
Then I can start on the wings.

No comments: