Roger wrote:
On Mon, 22 Aug 2005 18:06:14 -0700, Scott Moore
wrote:
snip
I disagree. A battery backed up electric AI is not cheap, but compared to all of the
components in a full vac system, it is, and its far more reliable. Even HAVING a
current VAC system does not eliminate that cost, since the MTBF for a vac pump is
down below 1000 hours, meaning you are going to have to change it soon in any case.

Mine has a couple thousand on it and is still going strong.

Do you have a wet pump? I would not fly hard IFR with a dry pump with
much over 500 hours, and I do have a standby vac. The "M" in MTBF means
half of the pumps last longer than that time, but it also means half
lasted less. If the ceilings are 1000' I'm not rolling those dice.

-cwk.