Don Dunbar wrote:

Hi Paul and group,
I have been reading with interest all the info posted on this subject as

I am at the stage of deciding what to do in regards to instruments.

I fly a Eagle 150 which has electric Attitude indicator, this instrument

is very unreliable and needs to be reset every few minutes.

Is this typical for electric Attitude indicators.

I don't think so Don. I don't know about that brand but electric attitude

indicators

are almost universally used in airliners as back up the the vacuum system. PL

My friend has a system in his Banaza with two air pressure sources for

his instruments, the normal pump and a 12 volt pump with non return valve in
each delivery line. He runs up the electric pump on the ground before
startup and checks all the instruments and 12 volt DC pump out.

I have done some research and found that the Attitude and Gyro require 2

to 4 inches of mercury vac or pressure, this is equal to 1 to 2 PSI. I don,t
have a flow requirement yet but am working on this.

I have also tested a few air pumps with the following results which I

don't think are suitable at this stage but will post the results as they may
be useful for door seals etc.

Pump 1#    2.2 kg or 5 lbs. in weight,  with 30 psi output. I have not

checked the flow rate or running amps but will do so if this is any interest.

Pump 2#    1.2 kg or 2.64 lbs. in weight,  with 28 psi output. As above

if any interest.

Looking for comments.
Regards Don

Most gyros need vacuum, not pressure.

Bill Freeman

True Bill but if it is a positive displacement pump there probably
is a correlation.

Paul Lamar
 
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