Sunday, May 20, 2012

Nose Cowl - P/N 7016

I've learned to gas weld aluminum while working on my Cessna 140 project so I decided now was a good time to work on repairing the nose cowl.  It's in pretty bad shape.  Someone has cut holes in the top and louvers in t he bottom.  The outer shell (P/N 7018) is spun from .040" soft aluminum.  The cost of getting a form made and having someone spin such a large piece (25" dia. x 12" deep) is beyond my budget. Making one without spinning it would require forming sections and welding them together so fixing this one seems a better plan.

The stiffness of the cowl is created with a former (Collar P/N 7019) which is formed from 1/2 hard .032" aluminum.

The first step is to strip the paint so I can work on the bare aluminum.  I've tried several strippers and I think I've found one I like.  It's Zip-Strip Contractor Plus paint and finish remover.  It has all the nasty stuff in it that makes a good stripper work and it washes off with water very nicely.
With the paint and bondo removed it's obvious the plane this was on went on it's nose.  The cowl was roughly hammered out and it's pretty rough.

The top is in very good condition.  The holes will be easy to fill and there is a little wear where the belt buckle rubbed.  The cowl is all held shut with a leather belt and metal buckle.  Because the top is so good the worst I'll have to do is cut out all the bottom and replace it.  That's still better than making the whole thing from scratch.

There are some other areas which need fixing as well.  There are some cracks around the bolt hole where it bolts to the engine.  The is also a piece splice on to the bottom edge and a piece cut off near one of the holes.  I'll weld on some pieces to repair these areas.

With the paint mostly removed I've separated the spinning and the collar.
The collar has some pieces of spruce 3/4" x 1" nailed to the front as a stiffener and a .148" wire formed into the edge of the oval opening.  I only bought a quart of stripper to try it out so on Wednesday (old folks get 10% off) I'll get some more stripper to finish cleaning up the parts before starting work on them.  Fortunately I have the drawings for these parts so I'll be able to repair them correctly.

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