Inside Look - The Vacuum Pump

[@billyt511]

Recently, I had vacuum pump go out during VFR flight. For me, it was no big deal. I first noticed that my attitude indicator had "dumped". Checked suction gauge and 0 suction. DG seemed okay at first but as gyro spooled down it became inaccurate.

[@ytirucsbo]

Thanks for this. I've understood what the vacuum system does, what instruments rely on it etc, but never how it actually works. Thank you.

[@blueeyeddevil002]

Todd is the best instructor I ever had and it wasn't even close.

[@JeffreyinChina]

thank you !!

[@azarpour]

Excellent video! Thank you for sharing this and explaining it.

[@captmulch1]

Thank you!! First time I have seen a vac pump dismantled.

[@fpsOklahoma]

Should do a video on checking the wear via the hex bolt with the vernier gauge.

[@H60ace]

I appreciate the video! I’m deciding weather to overhaul out buy a new one.

[@yuriys3164]

Thank you for showing the simple yet very effective design of the pump! I did not see any other videos on inside look-could you link others? Thanks again!!!

[@Ezel21love]

I like the way you explain thing including regulations of course.

[@Shiftypop]

I have an old air pump about half this size with the same sliding card type of setup. Mine isn’t graphite impregnated however. I’m going to attempt to make my own graphite and epoxy cards just to see if I can (it’s not for aviation, btw). I’m a little surprised they’re designed to fail like they are. I’d have thought a wear pin, like on automotive brake pads, would give notice of impending pump suicide… Thanks for the video!

[@CaptainSuarez]

Excellent video 👌🏼

[@ToddShellnuttCPC]

Glad you liked it!

[@MattAllenTeller]

Now I know how to take it apart and put it back together but I still have no clue how it actually works. I see stuff spinning in there but what does that have to do with creating a vacuum?

[@mikemcdonald4831]

He put it together backwards. Spins counterclockwise and clockwise

[@toddshellnutt540]

Good call - I simply put it back in the way I opened it the first time - so must have been why the mechanic said it wouldn't work.

[@theunisjoubert6298]

I also noticed it

[@michaelburke5750]

In optimal condition, how much vaccuum is this pump capable of pulling?

[@ToddShellnuttCPC]

Air-driven gyro instruments are designed to operate with a pressure differential of about 5 inches of mercury (about 2.5 psi). The pump is designed to produce plenty of airflow to spin the gyros even when the engine is idling on the ground. At normal flight RPMs, its capacity is much greater than necessary (as much as 20 psi). To maintain relatively constant airflow through the gyros, the regulator permits enough ambient air to leak into the system downstream from the gyros to limit the pressure differential across the gyros to about 5 in. Hg. The regulator is adjustable and has its own foam air filter to protect the pump from contamination. The cockpit vacuum gauge is connected to read the pressure differential across one of the gyro instruments (usually, the attitude indicator). The gauge normally has a green arc between 4.7 and 5.2 in. Hg. The vacuum regulator is adjusted so that the cockpit gauge reads about 5 in. Hg. Sorry for the long reply, just wanted to make sure that I covered the question for you. I have sent an email to the manufacturer for the full capability of the pump, I am not aware of the absolute max it can pull.

[@michaelburke5750]

@@ToddShellnuttCPC Thank you for the information.

[@pilotactor777]

Ive been experiencingvaccuum pump failures-way below the hourly prediction.Any ideas why?

[@ToddShellnuttCPC]

Almost every case of premature dry vacuum pump failure can be traced to one of three causes: contamination, overstress, or faulty installation.