Grumman AA5 VAC pump removal/reinstall

[Mark Nestler]

Does anyone have any experience with the removal of the Dry VAC pump on a 1975 Grumman AA5 Traveler (Lycoming 0-320 E2G)? Can the pump be removed without removing MAGs/Oil filter or any other accessories? Do I need to purchase the special VAC pump removal tool or will ratchet open ended wrenches do the job? (Pump failed and it will be reinstalled with a new pump).

 

[Magman]

How much work do you really want to put into this? Sockets , crows feet and standard wrenches will not work for me.

A screwdriver and all-purpose tool ( hammer) will allow removal of the one #&@*¥€ nut but is not recommended

for installation.

So you are left with borrow, buy or build.

A bud took some wrenches and heated , bent , brazed and ground up a tool that works great.

Some of the tools available work well, sometimes.

Good luck.

 

[Gary Ward]

Does anyone have any experience with the removal of the Dry VAC pump on a 1975 Grumman AA5 Traveler (Lycoming 0-320 E2G)? Can the pump be removed without removing MAGs/Oil filter or any other accessories? Do I need to purchase the special VAC pump removal tool or will ratchet open ended wrenches do the job? (Pump failed and it will be reinstalled with a new pump).

Vacuum pump replacement was the first aviation repair I had ever done as the vacuum pump quit working on my first flight in my late friends 172. His AP mechanic inspected my work afterwards.
I bent up a 7/16" 2 dollar wrench to loosen one nut. I bent up 2 wrenches using map gas but only needed the 7/16".
I believe the pump was still good? but the plastic drive coupler failed. Could have meant the pump was failing? My friend bought a rebuilt pump to go on it.
Caution: I could see oil on the plastic coupler and that meant oil could get in the new pump and effect the new coupler. My friend didn't want to put a new seal in so I put the rebuilt pump on. Sure enough I found it leaking oil again shortly after install. I made my friend buy another pump and new seal and I got to do it second time if he wanted me to fly his plane.

Use no sealer anywhere, depending on what you find You would be best to replace filters and be sure the vacuum system is clean inside.
Couple months later 2 G-5s were installed and I removed the vacuum system and sold the vacuum pump to my buddy for his cheerokee. Been 5 years now with no vacuum pump.

 

[Mark Nestler]

Thanks, My plane is tied down out in the Florida sun and don't want to get in over my head on this project. I only quickly looked at the right side of the VAC pump to get a model number and went home to see what Youtube videos were available. Couldn't find much in the way of a useful video, just the complaints about the one nut. My plane is about 30 minutes from where I live and was most interested in knowing if I have to remove any other components to get at the lower left nut. I don't have tools to time the MAGs and oil filters are extremely hard to come by. If I just have to remove 4 nuts and a couple pipe connections I'll go ahead with the project. Otherwise, my annual is next month and I'll put it off and hand it over to the A&Ps.

 

[Gary Ward]

Sorry I have no experience working on the E2G. Got a picture? Always take pictures to show to your AP mechanic. It was not hard on a 0-320 H2AD as the pump was right on top.

 

[Dan Thomas]

The E2G engine will be a lot harder than the H2AD. Mags are in the way, sometimes the filter. The H2AD's dual mag leaves more room. That special vacuum pump wrench pays for itself real soon if you don't have the means and ability to use a torch and reshape a wrench.

If the pump failed it was either because the vanes were worn past limits, or the plastic coupler aged out and broke. Six years is the limit for the coupler, and people like Cessna ask for pump replacement at 500 hours unless the pump has a provision for vane wear inspection. Tempest and Rapco have that, and nobody else AFAIK. With that inspection port you can run that pump right up to the vane wear limit and get the most time out of the pump without risking failure in flight (unless, of course, you fly 50 hours a year and the ancient plastic coupler breaks).

 

[chemgeek]

If the pump failed it was either because the vanes were worn past limits, or the plastic coupler aged out and broke. Six years is the limit for the coupler, and people like Cessna ask for pump replacement at 500 hours unless the pump has a provision for vane wear inspection. Tempest and Rapco have that, and nobody else AFAIK. With that inspection port you can run that pump right up to the vane wear limit and get the most time out of the pump without risking failure in flight (unless, of course, you fly 50 hours a year and the ancient plastic coupler breaks).

I concur based on experience in my AA5. About half my vacuum pump failures have been coupler issues. The rest were infant mortality well before 500 hours and 6 years. At 500 hours, you are definitely on borrowed time. I think I only had one pump make it that far. I pulled the vac system after installing dual G5s. Good riddance. One less issue to deal with IFR.

 

[Dan Thomas]

I concur based on experience in my AA5. About half my vacuum pump failures have been coupler issues. The rest were infant mortality well before 500 hours and 6 years. At 500 hours, you are definitely on borrowed time.

A vacuum pump on a Lycoming should run for 1100 hours or so. Continental spins their faster so they wear out sooner. Keeping the pump cool helps.

But short life, 500 hours, is an indication that the lines are not being cleaned out after a pump grenades. When the fail suddenly, the vacuum in the lines and instrument cases will suck carbon debris back from the pump, and the new pump then sucks in that junk and scores itself up and some life is lost right away. The pump's installation instructions (that come with every pump) warn the mechanic about that, but cleaning out lines is a lot of work. All of which argues for the Tempest or Rapco pumps, and checking their wear as per instructions. Usually the first check is at 500 hours, then every 100 hours thereafter.

From the Tempest Installation and Operator's stuff:




https://tempestplus.com/wp-content/uploads/2019/01/AIA114-100110.pdf

 

[Magman]

There is are 2 150’s ( 66 & 67) that have the never oh/d wet pumps still installed.

Not unusual is my take.

I have changed 1 wet pump and probably about a hundred dry junk.

Biggest piece of crap ever foisted on the Aviation Community .

Right up there with D Mags.


Dan’s comments remind me of my neighbors event.

Cherokee 235 - Night Take off heavy with fuel.

Vacuum Failure and associated gyros.

AutoPilot followed gyros winding down.

Unable to overcome the A/P disconnect ( he works with concrete ) the gyrations were wild

until he shut it off.

Long story short- A gyro failed internally and parts migrated to the vacuum pump which

caused it to fail.

My recommendation is a filter between the gyros and the pump inlet.

The Central Filter only affects air going into the instruments.

Some aircraft have them . If IFR ops it should be all.

 

[Mark Nestler]

Vacuum Pump shaft was sheared as expected. Managed to install the pump without removing any accessories. A little tight on lower left nut but I used the special wrench to hold nut in place (with oil filter installed did not have room to turn wrench) and then tightened the other 3 nuts to force the stud and nut to remain in place. Then loosened the top 2 nuts and right lower nut just enough so I could rotate lower left nut and start it threading onto the stud using the tip of one finger and special tool. About 2 hour job to clean out vac hoses and install.

 

[Gary Ward]

Vacuum Pump shaft was sheared as expected. Managed to install the pump without removing any accessories. A little tight on lower left nut but I used the special wrench to hold nut in place (with oil filter installed did not have room to turn wrench) and then tightened the other 3 nuts to force the stud and nut to remain in place. Then loosened the top 2 nuts and right lower nut just enough so I could rotate lower left nut and start it threading onto the stud using the tip of one finger and special tool. About 2 hour job to clean out vac hoses and install.

Thanks for the follow up, glad you got it installed without removing other stuff.

 

[Dan Thomas]

Vacuum Pump shaft was sheared as expected.

Did the pump turn freely? That plastic drive shears to save the engine's accessory drive gears when the pump's over-worn vanes cock and bust the rotor and jam the pump. If the pump still turns freely, the drive failed due to heat and age.

Here's one that's about to fail. Note the vanes cocking, wearing the slots, just about to jam and bust up the pump. Note the cracked rotor.



And here's a failed one:

 

[Mark Nestler]

Yes, the pump still turned freely.