Hi there,
This post can be entitled as the dirt, grime, sweat and goo of aircraft restoration.
Here is the why:
Our aircraft is a representative of an airframe that has been built quite well, by Utva Pancevo (now Serbia), but has deteriorated during each of the major overhauls it underwent.
One small thing that wasn't really an airworthiness issue was the use of really bad quality paint
Here you can see the inside of the fuselage behind the the throtle/mixture quadrant and the flap lever.
You can also see that the original cockpit colouring was a bit lighter, bluish shade of grey. This is also evident inside the prototype in Zagreb technical museum. Since we want to return the aircraft to stock 1962-1965 condition, this top coat had to be removed. The point was that it had to be removed in quite detailed fashion, due to the fear that the new paint will simply chip away with the bad one.
Therefore the past days were spent sanding away the fuselage.
Here is a portion behind the instrument panel. The left side is not sanded, but the right one is:
One thing that is also done at this stage is the removal of the cracked glue beads. The glue is about 50 years old and still has very good mechanical properties, except the fact that for some reason the beads crack and chip.
The biggest bonus of this huge effort of sanding down the whole fuselage is the fact that during this process, you really inspect every portion of the fuselage in minute detail.
These are the mistakes you find (a few centimeters of skin-to-cockpit half frame separated)
These are only the debris from cleaning up ''the last few'' glue joints at the instrument panel forward area.
And here is the fuselage finished. Note the bluish shade of gray:
But the worst part of this job actually happened inside the aft fuselage behind the cockpit.
First of all we were a bit suspicius about a few gussets in the frames and we removed them. Some of them were indeed necessary to remove, but most not. This crappy image shows the fuselage looking aft toward the tailgear bay.
Then the whole fuselage was cleaned and sanded. We will also add some strengtening blocks to the frame-longeron connection, but the structural work was a lot less, then first expected.
The biggest problem was the fact that there is no room to work in the fuselage. Here is a picture of Marko removing one of the frame gusets. All work is done from the wrist, which is very tiring. This and eyesight is one reason why I personally belive that restoration shops with younger guys have an edge above the ones run by gents in their sixties.
So, what now. First we have to finish the remaining sanding of the aft fuselage. Then we have to rectify the compression damage to the airframe due to overtorging the fittings bolts like this:
or this:
In the meantime I am also working on the fuel system. The fuel tanks were cleaned externally and the innards were video-scoped. No corrosion present, but one is very, very dirty. One the tank, you can also see all of the aluminium L-sections that go inside the station, which were cleaned, nicks polished off and are now ready for plating. Finding a shop that plates in this green shade was also a huge problem.
And there you have it! A huge amount of work, for almost no visual result.
Dirt, grime, sweat and goo of aircraft restoration
Login
Register
FAQ
Search
