Instrument warning light

[warren.huisman]

I have an instrument warning source inop light that is lit. However, I have no malfunctioning instruments and the vacuum is reading in the normal range. Before I take the glare shield off and start following wires, anyone have any idea what this warning light is indicating??

 

 

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[N201MKTurbo]

It looks like it is part of a Precise Flight standby vacuum system. There should be a flight manual supplement for it.

[PT20J]

Well, part of the placard is missing but it seems to say INSTRUMENT SOURCE xxxxx INOP WARNING and it's next to the knob labelled PULL STBY VAC ON, so I'd guess it's a low vacuum warning light. Is that one of those manifold pressure vacuum backup systems? There should be some sort of supplement in the POH.

[PeteMc]

Good chance that your primary vacuum pump has failed and the Precise Flight backup pump has taken over.

But like the others have said, you need to check the manuals you have.

[47U]

On 5/1/2023 at 10:19 AM, warren.huisman said:

Before I take the glare shield off and start following wires

I’m guessing the vacuum line to the low vac switch is compromised which is why the light is on.  Before tracing wires, trace the vacuum tubing to the switch and you might find your problem there.  It’s a very small hose and doesn’t have a hose end, it just pushes onto a small nipple on the switch.  This excerpt from the Precise Flight install manual might help visualize what you’re looking for.

 

[warren.huisman]

I’m guessing the vacuum line to the low vac switch is compromised which is why the light is on.  Before tracing wires, trace the vacuum tubing to the switch and you might find your problem there.  It’s a very small hose and doesn’t have a hose end, it just pushes onto a small nipple on the switch.  This excerpt from the Precise Flight install manual might help visualize what you’re looking for.

 

This is exactly what I found. It seems the hose was linked where it connected to the main vacuum line. All good now!


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[47U]

40 minutes ago, warren.huisman said:

All good now!

Great news… sorry I was late to the game.  

[warren.huisman]

Great news… sorry I was late to the game.  

No worries. I actually had it fixed earlier this week. I confirmed it was actually fixed flying today!


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[carusoam]

Keep an eye out for people selling off their electric back-up vac pumps…

This particular system has many limitations that are important to be aware of…

It only provides the right vacuum under certain conditions… that the pilot needs to be familiar with… before it is needed.

 

The electric back-up removes the need to adjust MP to produce good vac.  

of course… a back-up AI with its own battery is really good too.

Best regards,

-a-

[warren.huisman]

Keep an eye out for people selling off their electric back-up vac pumps…
This particular system has many limitations that are important to be aware of…
It only provides the right vacuum under certain conditions… that the pilot needs to be familiar with… before it is needed.
 
The electric back-up removes the need to adjust MP to produce good vac.  
of course… a back-up AI with its own battery is really good too.
Best regards,
-a-

It’s a good idea, but I only use vacuum for the backup AH which drives the autopilot and vacuum speed brakes. I’ve considered getting an electric back-up pump but I’m already fairly light in the useful load department.


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