dmmartindale (12/31/82)
There is an article in the most recent "Flying" about adding an electrically- powered auxiliary vacuum pump. The idea is that instead of having a second engine-mounted pump which wears out and has to be replaced periodically, this one should be good for the life of the plane. Also, you could add it to any plane while a backup engine-mounted pump requires an engine tooled to accept it. Of course, it's more expensive than a second engine-driven pump - the electric motor and associated parts ran many hundreds of dollars.
cfiaime (01/03/83)
The next question is: what happens if the vacuum pump is ok, but the associated plumbing is broken (I have seen it happen)? You still need to stay current on partial panel IFR. Also, instead of an electric vacuum pump, why not install a two-inch backup electric horizon? It should be about the same cost and the redundency of an entirely different power source would be nice. Jeff Williams BTL - Indian Hill
dmmartindale (01/04/83)
A backup vacuum pump has at least two advantages over a backup electric attitude indicator - your directional gyro stays working too, and you don't have to figure out where to put the extra attitude indicator. It would have to be somewhere you can see it reasonably well, and panel space tends to be pretty tight on the smaller 4-seaters when equipped for IFR.
ark (01/05/83)
I think that a third advantage of a backup vacuum pump is that it is much cheaper than an electric attitude indicator. Last time I checked, the only electric attitude indicators available were staggeringly expensive -- starting at something like $7,000! This may well have changed, and I may be wrong, but...