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Educate me about vacuum pump

Vlad

Well Known Member
I just got a nice gift a set of clean low time vacuum driven gyros (thanks JohnR) and I need a pump and associated plumbing. How long usually vacuum pump last? Used or new? Please educate me. :)
 
Went thru about 10 of 'em in the Bo. About 600 on the average. Two failed under 100 hours. Seems like one went 1200 hours.
 
Vacuum pump

Well, the wet vacuum pump in my Cessna 150 has lasted over 30 years that I have owned it, and maybe longer than that. On the other hand I have heard that dry vacuum pumps are prone to self destruct at any time up to around 500 hours.

Either pump has a main rotor with several vane slots in it. In the case of the wet pump, the vanes are steel and the pump is lubricated internally with engine oil. The discharge line from the pump goes into an oil/air separator with the oil being returned to the engine sump and the air discharged overboard. The dry pump was an "improvement". The vanes are self lubricating carbon/graphite and thus the pump is "dry", that is it needs no lubrication from the engine oil and needs no oil/air separator. BUT, the vanes are more fragile and do not last anywhere near as long as the wet pump.

After understanding this I decided both technologies were obsolete and I'm making my RV-9A fully electric with EFIS displays.
 
1st one in the RV lasted between 700 and 800 hours. 2nd one lasted almost 2,000 hours. Third one was removed working with between 600 & 700 hours.

I overhauled the 1st vacuum pump and still have it sitting on the shelf. If you want it, it is yours.

Vacuum system removed from my RV-6 less than a year ago to upgrade to two G5s and GMU 11.

Both gyros sold through VAF. Not much of a market for vacuum stuff in the experimental world.
 
Vlad, I removed the vacuum system from my Cessna 150 that I recently purchased and installed the Garmin G5 AI and HSI units. I do not know if the pump was working, but you can have it and the vacuum regulator and filter if you want them.

I will be in Mount Holly next month for several weeks and I can bring them up there if you want. The 150 is in a hangar at Flying W.
 
The graphite vanes should be good to TBO/2000hrs, but, as others have said, they are very sensitive to FOD. Anything that can impede their smooth sliding along the wall can break a vane. Make certain you clean everything (gyros, hose, pump) prior to installation. Early failures are often blamed on small carbon chunks from the previous failure getting sucked into the pump.
 
Get a sigma tek. they are built way better with a metal vane holder and vanes that are strong like carbon fiber. compare that to the fragile carbon like pencil lead vane holder and vanes in a different brand such as rapco.
 
From the Malfunction database that I revised a few years ago the dry pumps have an MTBF of about 500 to 600 hrs. That said, If you decide to go head with a vacuum system, I have some of the other components, like fittings, filter and regulator if you need them.
 
Vacume system :-(

Vlad, I used vacuum systems (gauges, pumps, gyro's) for years. My advice would be to sell the items you got and use the moneys to help buy an electronic replacement, G5 or similar. You'll spend a bit more but it will pay off in the long run and be much more reliable and provide additional flight info.

Steve
 
Vlad, I used vacuum systems (gauges, pumps, gyro's) for years. My advice would be to sell the items you got and use the moneys to help buy an electronic replacement, G5 or similar. You'll spend a bit more but it will pay off in the long run and be much more reliable and provide additional flight info.

Steve

Ditto what Steve said. Most people consider dry pumps to be on borrowed time after 500 hours, but it's not uncommon for them to fail before that. I was at an AOPA seminar a couple years ago and they threw up a stat that something like 1/3 of all vacuum pump failures in IMC are fatal. That was enough to convince me they weren't worth messing around with.

DEM
 
I just installed a glass cockpit. If you plan on using a vacuum pump, I will send you the one I removed, with the regulator, filter, lines & fittings, and the suction gauge for the cost of shipping. If you get enough donations, that should keep you going for many years! You can rebuild them yourself. Go with the carbon blades and replace the shear coupling. Vac pumps and magnetos are probably the least reliable components on the plane.

Don

I just got a nice gift a set of clean low time vacuum driven gyros (thanks JohnR) and I need a pump and associated plumbing. How long usually vacuum pump last? Used or new? Please educate me. :)
 
The dry pump on my -4 went ~800 hours before giving up the ghost. Put in a Dynon D10A and dropped 8lbs of associated stuff out of the airplane along with it.
 
I just got a nice gift a set of clean low time vacuum driven gyros (thanks JohnR) and I need a pump and associated plumbing. How long usually vacuum pump last? Used or new? Please educate me. :)

What you really need is a nice shelf to display them on, next to some test-tube radios and buggy whips. :)
 
Thank you all. Can?t wait to have traditional gyros spinning again. Would appreciate installation tips and tricks. If anybody has a reference and how to?s please post here. I am on the road now and my browsing capability is limited. :)
 
Thank you all. Can?t wait to have traditional gyros spinning again. Would appreciate installation tips and tricks. If anybody has a reference and how to?s please post here. I am on the road now and my browsing capability is limited. :)

HA! The only guy in existence putting vac pumps and mechanical gyros BACK into his plane!!:confused::confused::eek::p
 
Vlad - a couple of tips for you...

1) remember the FLOW direction. It starts with the filter, then the regulator, then goes through the instruments, then through the pump where it exhausts to the outside world

2) when building your hoses you will create all manner of rubber cuttings etc within the hoses. This "junk" is what kills vacuum pumps. Cleanliness is next to Godliness when it comes to vacuum hoses and fittings.

3) in order to prevent "junk" from being peeled off the inside of the hoses as you push them onto fittings, lubricate the open end of the hose very lightly with DC-4 or similar lubricant. I use a Q-tip for this purpose - it takes only a little bit.

4) use new hose. It's cheap, and old hose will be full of "junk" that will likely cause premature pump failure

5) if you are installing a vacuum system for the first time, please, please, please make sure you have a vacuum gauge installed in clear sight of the pilot. (I have no idea how Cessna managed to certify their airplanes like the C172 with the vacuum gauge waaaaay over on the right side of the panel.) If you can do it, I'd mount the vacuum gauge very close to the attitude indicator since failing vacuum can cause the attitude indicator to provide false indications. It can be an insidious failure - a functioning vacuum gauge in the pilot's line of sight is about the only protection you have from the dangers of relying on an incorrect attitude indication resulting from vacuum failure.
 
A special wrench is needed when installing one of the nuts on a vacuum pump unless you really want to cuss.
 
Vlad - a couple of tips for you...

5) if you are installing a vacuum system for the first time, please, please, please make sure you have a vacuum gauge installed in clear sight of the pilot. (I have no idea how Cessna managed to certify their airplanes like the C172 with the vacuum gauge waaaaay over on the right side of the panel.) If you can do it, I'd mount the vacuum gauge very close to the attitude indicator since failing vacuum can cause the attitude indicator to provide false indications. It can be an insidious failure - a functioning vacuum gauge in the pilot's line of sight is about the only protection you have from the dangers of relying on an incorrect attitude indication resulting from vacuum failure.

+1
I?d go further: get an AI with built-in loss of vacuum flag, or, at a minimum, a large bright red loss of vacuum warning light.
 
not sure what your goal is but a stratus with your iPad can add another attitude and wx source to your plane.
 
If you must...

Vlad you madman!
Here is a great link to vacuum system installation and associated plumbing. However, to quote my Dad when I was in HS about delivering a date to her home late:
"I wouldn't advise this".
Having been an A&P most of my adult life and had to repair/troubleshoot vacuum systems, I grit my teeth at the prospect of owning and flying one.
Like you, I have flown many different complex aircraft including military and civilian Jets with complex systems, the overall question is why borrow trouble? More than anything for me, the pump and hardware rob you of around 3HP. It's all about the ponies...

Simplicity is a virtue but if you must: https://www.experimentalaircraft.info/articles/aircraft-vacuum-gyro-system.php

До скорого!
Smokey
 
Last edited:
Vlad, I have sent you several PM's over the past week. Although I hit "send", my post are not showing up in the note string.

I am in the area and have the instruments that we talked about if you still want them. I will have free time starting Wednesday, 5 May.
 
Vlad, I have sent you several PM's over the past week. Although I hit "send", my post are not showing up in the note string.

I am in the area and have the instruments that we talked about if you still want them. I will have free time starting Wednesday, 5 May.

Roger that Noel! I am on the go too and online comms are interrupted. Will catch you at KVAY please keep that pump.
 
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