Powder Coat on 4130

But if the hairline crack doesn't break the paint film the oil will
still be contained. Besides the oil, weld a boss on a longeron tube end
and install a tire valve and pressurize to 100 or so psi pressure during
the annual. The pressure should be enough to make the paint film fail
and cause leakdown. Find the leak by listening or water/soap.

Llama helicopters charge the truss permanently with dry nitrogen and
have a pressure gauge that is in view behind the cabin and can be
checked on a DI.

John

Now that is an interesting way of doing it. Just
check the pressure on preflight, and you'll know
there aren't any cracks if it's still holding
pressure. Plus, if charged with an inert gas such
as nitrogen, helium, or argon, you also know there
will not be any corrosion inside the tube.

Don W.

"Don W" wrote in message
. ..

Now that is an interesting way of doing it. Just check the pressure on
preflight, and you'll know there aren't any cracks if it's still holding
pressure.

Well . . . you will know that the gauge pointer hasn't moved. For fire
extinguisher classes, I had a demo extinguisher which was cut open so's you
could see the interior. The gauge still read in the green.

Rich S.

Rich S. wrote:
"Don W" wrote in message
. ..
Now that is an interesting way of doing it. Just check the pressure on
preflight, and you'll know there aren't any cracks if it's still holding
pressure.

Well . . . you will know that the gauge pointer hasn't moved. For fire
extinguisher classes, I had a demo extinguisher which was cut open so's you
could see the interior. The gauge still read in the green.

Rich S.


It's probably overkill to have a gage reading continuously anyway. The
gage would change for some reason and you'd panic and ground your
airplane. Better to just hook something up during an annual.

John