On my Hirth G-40 Gearbox; the vent was located on the top. I was constantly getting residual oil on my prop and tail. While at Bensen Days; I saw Dave Seace machine had a Banjo Bolt in that location with a piece of hose running up to the mast.
There was not enough room to mount that way on mine (because of the pre-rotor); so I put the banjo bolt into the top/upper oriented plug hole and routed the hose to a location up on the mast. Works great. Any oils which get splashed out the hole and travel up into the tube, just condense and drain back down into the gearbox.
Here is a photo I took during Mentone 2015. I had a clutch issue and had to remove the gearbox. On the left side of the gearbox, you can see the Banjo Bolt.
The tube works but in mome cases you need to put a chamber on the end of the line to capture and hold the oil, sometimes filling this chamber with pot scrubber material helps if you are still loosing a little oil.
NO Way !!! Someone even cares ! I have not been in much of a hurry sooo...... Tomorrow we will be wrenching on Andy's SH again but I am totally ready to fire her up. I will let you all know ! I am excited & thrilled but I give away so much of my time that I don't get my own stuff done.
BTW.....I did bump the key to try out the starter without the prop on & she fired instantly...woops. I know she will start & the prop is all torqued down.....what a beast she is !
Next.... run it , adjust the prop pitch, & check gauges & look for Check engine codes !