L3 fuselage question

[Aerco]

When I got my L3, there was a fishmouth external splice at the upper left rear longeron. I assumed it was a nicely done repair. Then I noticed it was on the actual fuselage frame drawings! And the only other L3 I have seen close up had the same splice. This is curious - anyone have any idea why this was done? If a design weakness was discovered and remedied, surely the drawings would have been changed. And a weakness would be more like an undersize tube that would be changed to a larger size, not a reinforced joint. I know enough about aircraft design and stress analysis to make this baffling to me, since I can't think of a condition that would warrant such a change.

I have seen splices in random places where the factory simply used up left over tubing, but that is different.

Any ideas?

[joea]

Does look like very nice welding!

[Doc]

Nice buildup spot for 5 tubes of equal diameter to join.