jls wrote:

I rebuilt one and the best A&P on the field rebuilt the other one, on 1966
and 1957 172's. Neither will hold nitrogen. What's the secret to getting
them not to leak.

I bought a complete O-ring kit from Trimcraft in Wisconsin. My personal
A&P told me that only one or two large O-rings were leak-prone and crucial
for replacement so I replaced those only, at his urging. Now I think I'll
install the complete kit, which includes at least 6 O-rings. How about it
A&P's who are Cessna savvy? What's the trick here to getting these struts
to stay up and not leak nitrogen? I know they are not leaking around the
Shrader valves. I have done too much testing with soap suds looking for a
bubble to emerge. Besides, both of the Shrader valves and the valve stems
have been replaced and are official Cessna parts.

The flight school A&P on the field says some of the struts just have to be
re-gassed with nitrogen occasionally, but that's not a satisfactory answer,
far as any owner would be concerned.

Thanks in advance for any good advice you can give on this frustrating
problem.



If its leaking around the lower O rings, then oil would be forced out.
As long as there is any oil in the strut, then it will be forced out
first (unless the airplane is laying on its back!) before nitrogen begins
to leak.

The only place nitrogen can leak is at the top, around the Schrader valve
or through it. Another possibility is a leak around the plug/metering
rod at the top (inside) of the strut tube. In this case, the nitrogen would
be leaking down the tube, and exiting through the hole in the fork.

MikeM