What is the purpose of aircraft main gear actuator vent hole?

Question

What is the purpose of aircraft main gear actuator vent hole?

Answer 1

I would agree with deep

I would think that it is a weep hole to tell if the rubber like seal is bad on the piston.

Answer 2

The only thing I can think of would be access from the downstream side of the actuator back to the resevoir in the case of a mechanical release of trapped pressure for an emergency extension. You could "technically" call it a vent... when in reality it is a valve that is turned to "vent" hydraulic fluid out of the line back to the resevoir and allow the gear to fall down into place. This is a common system on small general aviation aircraft.  In the event of a landing gear failure a typical proceedure would be to place the landing gear selector in the down position, pull the emergency gear release (which would activate said valve) and the gear *should* fall down into position and lock. Then you would use the manual pump to apply pressure to the down side of the actuator and force the gear into a locked position and hopefully give you the green lights.  I have had to do this proceedure many times for checkrides and real situations, and the reason for the vent is you have to release that trapped hydraulic pressure that holds the landing gear up in the retracted position (on some airplanes) and/or release the mechanical uplocks (on others)  But in anycase, I have never heard/seen/read it being described as a "hole"  Holes are not a good thing in Hyd systems.

Answer 3

I was thinking of my basic landing gear but too lazy to get my training manuals so i rely on my knowledge, I don't recall any hole in any actuator perhaps a vent line but not a hole otherwise fluid or air would leak out. As any actuator there are two ports in it 1. is the head end and the 2. is the rod end. from this if you want to extend the rod the pressure is put in the head end port in order to push the rod but the pressure remaining in the rod end would prevent it so the rod end port becomes the return line, and now the rod extend freely this is where your vent hole or line comes in it's main purpose is to prevent a sudden full extension of the rod by slowly venting or unventing so that extension or retraction is smooth but slow. that is always the purpose of a vent hole but in actuality it is a line like I said before you don't want hydraulic fluid coming out during extension/retraction then re-servicing after.

Actually it is a pressure dampener so pressure surging is eliminated you don't want to see any actuator jerking in its extension or retraction cycle.