[n86121]

Being a nerd, years ago I actually studied the hydraulic schematics in the service manual. BTW, it is NOT a great topic of discussion with fiends.

Anyway, my pre takeoff procedure is to taxi the gear handle DOWN while taxiing (or during runup).

This pressurizes and cycles the whole system.

How long the handle takes to pop back up from 'gear cycle down' to 'gear is down and locked' position indicates fluid level.

In the summer its about 4-5 secs. In winter a bit longer.

If it takes longer, it tells you the system low.

AND, if there is a leak and it doesn't pop back up because it can't hold 1200-1500 PSI (as I recall), or takes really too long, then you find out BEFORE you takeoff (Which is much better than AFTER).