Chuck wrote in message . ..

Hi group,

I have a Cherokee 180 that is IFR cert, but both A.I. and Turn
Coordinator are vacuum driven. With both driven by vacuum, a pump or
engine failure in IMC will leave you guessing if you're right side up,
turning, or pitching.

You mean the AI and Directional Gyro, no?

Does anyone out there have any experience with the STC'ed backup
vacuum pump kits? Is one maker's kit better/easier to install that
others? And is there any information available on reliability? I'd
hate to put in a "backup" system only to have it fail to work!

My 172 has the Precise Flight standby vacuum system, which is capable
of providing survival-level vacuum under specified conditions, namely
reduced throttle (less than 2100rpm) and below 8000'. Luckily this is
just what you're doing on an approach, so it works where you need it
to. The installation also typically includes a low vacuum annunciator
light.

http://www.preciseflight.com/standby.html

It's quite simple in and of itself, but there is a recurring
inspection AD that can cost a few hundred dollars depending on the
situation. It works by tapping the vacuum system into the intake
manifold with a bypass valve, so it works a long as the engine's
running.

What I like about this system is that I don't need to change my scan
to use it--I'm still navigating off the same instruments I use all the
time. Typically a backup electric AI is crammed into some odd spot on
the panel.

FWIW it was installed before I bought into the plane so I don't know
what it would cost to put one on. Almost definitely a good deal less
than a second vacuum pump.

Best,
-cwk.