I have just done the Mod 37 in situ. Without engine and without gear. With gear
and engine installed, it is impossible to do (in my humble opinion). The welding
was done by an approved aircraft welder (however it turned out that he is not
welding on a regular basis - only from time to time....) Heat barrier paste and
wet towels have been used.
The result of the job: slightly burned laminates on the bottom edges, a very
stiff bearing, a slightly bent bottom horizontal tube and in my opinion low
quality welds due to bad access especially of the 2 exterior reinforcing straps.
Allthough the result is quite disappointing, I believe that a real expert in
welding should be able to do a good job also in situ.
In my view the following is essential for success:
0. Remove engine and gear :-) Turn fuselage upside down.
1. Find a real welding expert !!!!! Someone who is welding every day for a
living!!! No hobby welder...
2. Use a jig or a spacer between the bottom horizontal tube and the middle
horizontal tube in order to prevent distortion of the bottom tube
3. Use heat barrier paste
4. Protect your laminate with sheet metal or similar
We also did the Mod.37 on an other aircraft with the frame removed. The job was
obviously easier but as we haven't used any jig or spacer the bottom tube was
slightly bent and also the bearing in the middle tube went completly stiff. We
had to remove the bearing and slightly file its inside to have it work again.
Maybe with a real professional welder we would have less problems...anyway the
job is not an easy one...
good luck
Klaus Dietrich
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