How to test vacuum system out of aircraft

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skipnsb

Filing Flight Plan
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skipnsb
My entire vacuum system from the regulator aft is out of the aircraft.
How can I test the system using some sort of vacuum pump attached to the regulator?
If I replace the 40 year old hoses, is therre anything more user friendly than the original hard thick hoses?
Do you recommend an inline filter be added between the vacuum pump and the regulator? if so, how?

Thanks again for any help, Skip
 
skipnsb said:
My entire vacuum system from the regulator aft is out of the aircraft.
How can I test the system using some sort of vacuum pump attached to the regulator?
If I replace the 40 year old hoses, is therre anything more user friendly than the original hard thick hoses?
Do you recommend an inline filter be added between the vacuum pump and the regulator? if so, how?

Thanks again for any help, Skip
Click to expand...

I have an electric vacuum pump that I've used to "power" the pneumatic systems in my airplane without running the engine(s) on the ground. I see no reason why you couldn't use something similar with those systems removed from the airplane.

What exactly is your goal here? Are you just trying to confirm that the gyro's work or diagnose some sort of existing problem?

Some airplanes have a filter between the regulator and the gyros. If the system is plumbed for pressure driven gyros this is pretty much mandatory to prevent carbon dust from a dry vacuum pump from contaminating the gyros. In a vacuum system this location of a filter is less common but can be useful in protecting the gyros from the debris of a pump failure. In the unlikely event of a gyro emitting parts or debris it would also protect the pump.
 
This is a project going back together, I just wanted to test everything before putting it back together.

Do you know how powerful of a shop vac would be needed to adequately test a 1968 Cessna vintage: Regulator, DG and AI?

Thanks, Skip
 
I would test that idea with a good (but dispensable) vac gauge before attaching expensy instruments!
 
Shopvac is way more than you need. You'll want a large bypass.
 
Let'sgoflying! said:
I would test that idea with a good (but dispensable) vac gauge before attaching expensy instruments!
Click to expand...

I've seen specs for a 2HP shop vac that claimed 50-60 inches of water with zero airflow. That corresponds to 4-5 inHg which is enough to power a gyro but you'd need more to test the regulator. I don't think you could hurt anything if you connected the vacuum cleaner to the regulator though.
 
Lance says you are good to go, so have at it. (he has the engineering smarts here, not me)
 
gismo said:
I've seen specs for a 2HP shop vac that claimed 50-60 inches of water with zero airflow. That corresponds to 4-5 inHg which is enough to power a gyro but you'd need more to test the regulator. I don't think you could hurt anything if you connected the vacuum cleaner to the regulator though.
Click to expand...

Didn't know our little pumps were so powerfull. A shop I used had an old vac to test but had a big bypass before the connection. Now that you point out the math it was probably for cooling rather than pressure.
 
ejensen said:
Didn't know our little pumps were so powerfull. A shop I used had an old vac to test but had a big bypass before the connection. Now that you point out the math it was probably for cooling rather than pressure.
Click to expand...

"Our little pumps" can produce a suction (pressure drop) of more than 10 psi or 20 inHg if you block off the airflow but at light pressures a shop vac will pump a significantly larger volume of air.
 
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