Every time I get in the aircraft and before I start the engine I notice
the attitude indicator is displaying a nose down and a left turn. Why
is that? Is there something wrong with the instrument and is near
failure?

KP

Your only concern should be whether or not it erects properly within a
decent interval...by the time you are taxiing, for example. When the vacuum
pump stops providing the force necessary to spin the gyro it is going to
come to rest in some unpredictable way.

Next time you shut the engine off, however, don't leave the cockpit for a
few moments, and listen to the gyros as they spin down...if there is any
kind of mechanical problem, you will hear it.

Bob Gardner

"KP" > wrote in message
oups.com...
> Every time I get in the aircraft and before I start the engine I notice
> the attitude indicator is displaying a nose down and a left turn. Why
> is that? Is there something wrong with the instrument and is near
> failure?
>
> KP
>

KP wrote:
> Every time I get in the aircraft and before I start the engine I notice
> the attitude indicator is displaying a nose down and a left turn. Why
> is that? Is there something wrong with the instrument and is near
> failure?
>
> KP

It is a gyroscopic instrument powered by vacuum or electric. When there
is no power, it is not going to work.

> Every time I get in the aircraft and before I start the engine I notice
> the attitude indicator is displaying a nose down and a left turn.

You just described the expected behavior. Why is this surprising to
you?

Are you expecting the AI to jump to level when you turn the master on?
-harry

It is weighted slightly off center to make up for the coriolis
acceleration due the rotation of the earth.

The weight makes it precess as required to appear to
be level.

And the erection mechanism is as others have pointed out...
takes the average downward vector and calls that level.

Bill Hale


wrote:
> > Every time I get in the aircraft and before I start the engine I notice
> > the attitude indicator is displaying a nose down and a left turn.
>
> You just described the expected behavior. Why is this surprising to
> you?
>
> Are you expecting the AI to jump to level when you turn the master on?
> -harry

KP writes the AI's orientation is predictable, ie nose down and left
turn.
Bob, should we really expect an unpredictable way, as you write?

Stan

On Thu, 5 Oct 2006 14:50:47 -0700, "Bob Gardner" >
wrote:

When the vacuum
>pump stops providing the force necessary to spin the gyro it is going to
>come to rest in some unpredictable way.
>Bob Gardner
>
>"KP" > wrote in message
oups.com...
>> Every time I get in the aircraft and before I start the engine I notice
>> the attitude indicator is displaying a nose down and a left turn.
>> KP