Cracked my Italian made 490 in the clamp area the other day. Likely cause - too much clamp pressure (maybe?)

I've always heard that masts are thicker where the boom attaches so I thought I'd saw through and see how much reinforcement is actually there.

Here's the break:


Here's the base thickness:



And here's the clamp area:



I can see that there is an extra layer inside the mast not much more that a sheet of paper in thickness. Re-measuring the wall thickness several times I can see also that the clamp area is indeed thicker, but only just (less than 0.5mm).

What have I learned?
1. Back off on the clamp pressure.
2. Buy RDMs from now on.

ikw777 said...


1. Back off on the clamp pressure.

Think of the forces that the boom clamp applies to the mast when rigged, and then think of the forces that go through the boom clamp while landing something like a backloop, or even just hanging your weight off the boom..

RDM means reduced diameter mast (i think)