Front strut rebuild

thyslip

I have had to get my front strut refilled twice in the past 3 months. Any idea how much it might cost to build it?

houston21481

Depends on what it needs. I had the same issue - every time the temperature dropped (I live in upstate NY, so that happens a lot), the thing would go flat.

In my case, the chrome on the strut was good, but the aluminum bearing that the strut slides through and holds the o-rings was badly pitted. I had that replaced a couple of years ago to the tune of $110 (incl. labor). No problems since.

houston21481

magman Wrote:
> Air can leak out the TOP. ( Unless there is no
> fluid in the strut).
>
> Fluid out the BOTTOM.

I wouldn't jump to that conclusion. Air under pressure will leak out of whatever point it can. In the example I gave above, I was not losing fluid, just air. The valve on top was fine. Because the bearing was pitted, the o-rings didn't seal well enough to keep the nitrogen charge in, but well enough to contain a viscous fluid.

GM

For those leaking fluid this works well. They even use it on the air----.


http://www.aircraftspruce.com/catalog/lgpages/strutseal.php

thyslip

It is not leaking fluid, just air (nitrogen) so I am hopeful it might be the valve. The seal was replaced at the last annual. Thanks for the responses.

houston21481

magman Wrote:

> How would the air in the upper part of the chamber
> leak THROUGH the
>
> FLUID to come out on the bottom?

Magman -

Fluids are not gas-impermeable. Any fluid with a gas over it will contain a partial pressure of that gas and pressuring the entire system will increase that partial pressure. If you give that gas somewhere to go, eventually, it will. Thermodynamics always wins.

Arguing about it doesn't change my experience: repeated nitrogen loss with no fluid loss evident, top valve was fine (it was replaced early on, did not solve the problem), replacing the bearing and improving the bottom seal took care of it.

My point for thyslip is the same as yours: a full rebuild is probably not necessary, he just needs to find where the system is leaking. I feel his pain. My problem was sporadic over a couple of years and it was maddening to drive out to the airport to fly only to find the strut flat.

And if thyslip's issue is the valve, that's wonderful. It's a far less invasive repair. :-)

flyguydon

It is not a specific pressure. You want enough pressure to have about 3 - 4 inches of the strut showing while at rest.

78TARROW

I had nitrogen loss without fluid loss in my Arrow. It was most likely lost a bit at a time when the gear was retracted. Never went totally flat but needed N2 top off twice in three months. Valve and stem were just fine. Had the O-ring and fluid replaced. It was a couple bucks for the parts & fluid and 1.5hrs labor. The cylinder and insert surfaces were in good shape. It had been forever since it had been serviced as the fluid had turned black. I'm not kidding. I had it serviced about three months after I bought the plane and it's been worry-free since. I'm having the mains done now during the annual.