Whats normal top off/refill of hydraulic fluid (337B)?

[Jhogan0101]

I seem to be losing fluid from the overflow vent.
Within 3 flights i had to topoff about a quart of fluid.
Whats considered normal?
If this isnt normal, what would cause this?

[n86121]

There was one condition where the system spits hydraulic fluid out over the side,
and it won't leave a stain UNLESS it happens to hit the pilot side gear leg in flight.

The fix was minor, the condition in the maintenance manual somewhere under landing gear.

[Frank Benvin]

Did you find out why your loosing fluid ?

[Jhogan0101]

Im in the process of testing. the fill screw was missing, im thinking that could have caused an issue. plugged it back up yesterday. ill report back.

[wslade2]

Be aware of air in the system which can cause the fluid to foam up and overflow.

[Jhogan0101]

yes. i did experience this when the nut on the elbow going into the rear hydro pump was loose and the threads wore out. it created a venturi situation and hydro fluid foamed out of the vent. took a while to find/understand what was happening.

anyway, this is different.

i have flown a couple times and it seems top off is minimal now. signs pointing to missing hydro fill screw causing the issue.

[wslade2]

Looks like the fill tube goes to the bottom of the reservoir. If so, missing that nut leaves tube open to a high pressure area from ram air. Can pressurize reservoir and possibly even bubbles the fluid introducing air or even foaming.

See attached link
Tube #68