It is “the latest tech” and it is cheaper.
I’m skeptical as well, but it is not my plane, and thus not my decision.
From what I’ve read, the wet pump seems to be the better of the two… but I’m still new to ownership and can barely point my way around an engine… learning as I go though, thanks to everyone for their help.
I have merged the two threads and cleaned them up 
I am not aware of an argument for going from a wet pump to a dry pump. What reason did your mechanic give?
I’ve been reading that wet pumps are better than dry ones because they don’t fail catastrophically, but gradually instead.
Both the mech that I trust and the local one (flying across the US) recommended to switch to a dry pump. So, listening to wisdom, we’ve done so.
But I have a sneaking suspicion that wet pumps are better…
Anyone with practical experience with both?
However the vanes also sometimes fail catastrophically for no obvious reason.
There is a bit of wet vac pump installation going on in the USA.
Today’s dry pumps have a window to inspect the vanes. That makes it possible to determine their condition and also not have a fixed replacement interval under EASA reg. I don’t think anybody really installs wet vacuum pumps anymore these days.
Just had a pump failure and the mech is recommending a dry pump as a replacement.
I’ve read up on the basic differences between wet vs dry pumps but I’d like to find out about the practical realities of operating a dry pump rather than the stock wet pumps on aircraft engines.
Does anyone have any practical experience and wisdom they’d be willing to share about this?
It is certainly true that the “hydraulic pump drive” on my IO540-C4D5D does have an oil feed (see the backup alternator thread) but I have not seen such a feed on my vacuum pump drive which is otherwise identical (or would be if Lyco had bothered to put in the right drive shaft in there…).
Maybe the hole is there but is normally covered by the dry vac pump gasket. If so, that is quite a potential for an oil leak because the oil feed hole is only about 3mm away from the gasket edge so if that little section of the gasket breaks, you will get oil squirting out of there at the full gallery pressure of about 70psi.
It certainly can’t come via the standard dry vac pump attachment point
the accessory drive attachment point must have this oil line, which I guess is blocked when using a dry pump.
On the Airwolf internet site FAQ they say:
A wet vacuum pump, commonly called a wet pump, is a vacuum pump that is internally lubricated by engine oil. All engines since the age of time, already have the accessory cases drilled for a wet pump so no additional modifications are needed from the installing mechanic.
I meant the wet pump
I wonder where the dry pump gets its oil supply.
What should a dry pump use oil for?
