Proactive vacuum pump replacement

[ScottM]

I am on my 2nd vacuum pump. The first one broke on me with basically no warning the first year I had my plane. It has been almost 600 hours of flight since then and I am wondering if I should just go and replace the pump.

I do have a venturi standby vacuum pump in my Cherokee. But was wondering how many of you just replace the pump at a set period of time or do you wait until it fails?

If you wait until it fails do you fly into IMC on a regular or semi-regular basis?

 

[wsuffa]

Nope. Proactive for me. I'll have to look back in the logs, but somewhere between 500 and 600 hours on a dry pump at annual. I also do the alternator belt every couple of years at annual.

 

[Let'sgoflying!]

Proactive.
Bought a used one and r&r'd it, installed.
R&r'd the removed one, kept as a spare til ~400hrs.
Rinse/repeat.

 

[Dan Thomas]

We buy inspectable pumps for our training fleet. Rapco, Airborne, and others have means to check the vane wear; Rapcos have a small screw in the side of the pump and they give you a little plastic dipstick to insert to check the wear. Airborne's is a pipe port in the rear of the pump, and looking though that you can see the vane ends through a small reference hole.

Both of these will call for 100-hour inspections beginning at the 500-hour mark . We do that (takes three minutes, maybe) and replace the pump when the wear is at limits. Never have failures. It's worn vanes that cause the rotor to shatter when they cock in their slots and jam the pump.

Pumps on Lycomings will last longer than those on Continentals. Continental pump drives turn faster.

Dan

 

[timwinters]

I replaced mine prophylactically at 3000 hours. Love my wet pump!

 

[SCCutler]

The guy from whom I bought my plane suggested that 500 hours was a good duration for replacement of the vacuum pump (pressure, in a Bonanza, but it's the same pump).

Mine failed at something like 488 hours. If you've got 600, it owes you nothing - replace it!

 

[poadeleted20]

My opinion is that the money is better spent on recurrent partial panel training. If you want to pick some number of hours to change your vacuum pump even if it's still working OK, mighty fine, but if you fly in actual instrument conditions and don't maintain good partial panel proficiency, it doesn't matter how many hours you change the pump at, because sometimes they fail quickly and sometimes they last over 1000 hours.

 

[Let'sgoflying!]

My opinion is that the money is better spent on recurrent partial panel training.

It sounds like a choice, we have to choose only one?
Some of us might do both!

 

[Steve]

It sounds like a choice, we have to choose only one?
Some of us might do both!

and some of us put in a fully redundant electrical panel...

 

[Tom-D]

Good old Pesco wet pump, on its second set of vanes since 1949

 

[SCCutler]

It sounds like a choice, we have to choose only one?
Some of us might do both!

Me, me!

and some of us put in a fully redundant electrical panel...

Me, me!

 

[Ranger]

Ron has an interesting point here, that holds especially true for those that go out and spend a wad of cash on electric backups. Do those electric backups come at the cost of solid partial-panel skills? In my experience, I see more pilots spend money on fancy cockpit toys rather than establishing and maintaining solid piloting fundamentals. As a CFI-I, I wouldn't recommend an electric AI to any IFR pilot simply because if they have a good set of IFR skills, it's a piece of equipment they won't normally use even when its available.

 

[wsuffa]

Ron has an interesting point here, that holds especially true for those that go out and spend a wad of cash on electric backups. Do those electric backups come at the cost of solid partial-panel skills? In my experience, I see more pilots spend money on fancy cockpit toys rather than establishing and maintaining solid piloting fundamentals. As a CFI-I, I wouldn't recommend an electric AI to any IFR pilot simply because if they have a good set of IFR skills, it's a piece of equipment they won't normally use even when its available.

If you're suggesting that without considering other factors, you're doing a disservice. What kind of flying does the pilot do? Where does he fly? What kind of recurrency does she do? What other equipment do they have? Are they buying a full system (HSI and horizon, like a King FD system) or just a backup horizon? Do they have backup electrical? Do they have backup vacuum? All that stuff factors in, IMHO. As does the question of whether they've got a dead horizon to start with - it may be incremental money to buy electric vs replacement vacuum.

When I bought my plane it had two vacuum AIs, a King electric HSI, a backup vacuum system, and an electric TC. While I have removed the backup vacuum system, I do keep the 2 AIs. At this stage, I might consider a backup AI with solid state gyros, but I am currently flying little hard IFR and do IPCs a couple of times a year. That doesn't make sense for everyone, and I'd pull the entire vacuum system if I could to cut down the weight in the front end of the plane. But that's. Ot cost effective at this point either.

 

[Ranger]

That's another issue with aviation discussions- too many "it depends on _____." All things being equal, an IFR pilot shouldn't be taught to use the AI very much in normal IFR flying. No matter how infrequent an IFR pilot flies, if they remain IFR current, they should retain the basic skills- which don't include normally using the AI. I'd recommend a backup turn coordinator, VSI, altimeter, or DG before I recommended a backup AI.

Also, I'm talking about pilots that elect to spend the money on these things, not those that buy an aircraft that may happen to have that stuff from a previous owner. And switching to an electric AI when the vacuum one dies has nothing to do with my argument in the first place.

All too often I'm seeing pilots get equipment upgrades, fancy gadgets and backup [fill in the blank] instead of solidifying their basic skills. The issue with this is that it gives them an immediate boost to their perceived abilities when in reality, it's another piece of equipment they have to manage when they can barely manage the basics.

 

[wsuffa]

And this is prima facia evidence of why there is no right answer. If I'm flying heavy IFR all the time with passengers, I may very well consider it good money to have a second AI. There is still the matter of personal preference.

The role of an instructor, IMHO, that flys with an experienced pilot is different from that of a less experienced pilot. In my view, an experienced pilot should receive hints, tips, and pointers, as opposed to a less experienced pilot that needs to develop good habits. I nearly tossed a CFI from my plane after he changed my Garmin 430 to track up without telling me what he was doing, whereas I fly north up. We then had a discussion where he told me that it was 'wrong' to fly north up, and I should never fly that way. I told him we could fly north up, or not fly, and that he wasn't to change my equipment settings without talking to me first. That's bad CRM on his part, and could have been outright dangerous in hard IFR.

Which points up another issue in aviation: pilots and instructors that have an imperious attitude and can't see that there are other ways to do thing, all of which are perfectly safe and a matter of personal preference.

That said, I prefer to minimize use of the AI, especially with an HSI in the panel.

That's another issue with aviation discussions- too many "it depends on _____." All things being equal, an IFR pilot shouldn't be taught to use the AI very much in normal IFR flying. No matter how infrequent an IFR pilot flies, if they remain IFR current, they should retain the basic skills- which don't include normally using the AI. I'd recommend a backup turn coordinator, VSI, altimeter, or DG before I recommended a backup AI.

Also, I'm talking about pilots that elect to spend the money on these things, not those that buy an aircraft that may happen to have that stuff from a previous owner. And switching to an electric AI when the vacuum one dies has nothing to do with my argument in the first place.

All too often I'm seeing pilots get equipment upgrades, fancy gadgets and backup [fill in the blank] instead of solidifying their basic skills. The issue with this is that it gives them an immediate boost to their perceived abilities when in reality, it's another piece of equipment they have to manage when they can barely manage the basics.

 

[SCCutler]

...


That said, I prefer to minimize use of the AI, especially with an HSI in the panel.

I was taught that the DG was the primary attitude instrument. Works for me.

And I have two AI's, two DGs (one is an HSI), and one of each is electric, the other of each is air.

Plus I have an S-Tec rate-based autopilot, which cares not one whit what the AI says.

I will take every advantage I can get, thanky very much.

 

[ajstoner21]

I don't know what side of the fence I am on.
On one side, replacing a vaccuum pump proactively every 500 hours sounds a good plan that many people follow. Although replacing it for "no reason" gets costly.

On the other side, I totally agree that you should have solid partial panel skills if it does fail.

So, this is what I think:
For the time being, as a VFR pilot, I would replace when it fails. If I wasn't flying often enough for whatever reason to be super proficient IFR, I would proactively replace it. If I was flying IFR very often, I would replace when it fails as I should be able to handle partial panel.

 

[bbchien]

The role of an instructor, IMHO, that flys with an experienced pilot is different from that of a less experienced pilot. In my view, an experienced pilot should receive hints, tips, and pointers, as opposed to a less experienced pilot that needs to develop good habits. I nearly tossed a CFI from my plane after he changed my Garmin 430 to track up without telling me what he was doing, whereas I fly north up. We then had a discussion where he told me that it was 'wrong' to fly north up, and I should never fly that way. I told him we could fly north up, or not fly, and that he wasn't to change my equipment settings without talking to me first. That's bad CRM on his part, and could have been outright dangerous in hard IFR.

BINGO! The advisory Circular says, "instruction must be appropriate to the student".

Trouble was, your CFI was less experienced that you. He can't handle small varations when he fact he should be able to handle "DTK up" or any other variation on the setup.

Sigh.

 

[Let'sgoflying!]

Although replacing it for "no reason" gets costly.

How much does everyone think that proactively r&r-ing a standard vac pump costs?
It's really a very minor expense to do this....compare it to being stuck in Podunk on Sunday, needing to get through some wx & home for work. Or worse yet, dealing with a failure in the clag; because despite the best of intentions, you never did get great at partial panel or you have let your training slip a little.

Pilots will drop $10,000 on a panel goodie or interior, but won't spend eighty bucks to save themselves a major inconvenience or maybe, their life?!
You know if you get aog over a blown pump, that hotel and taxi bill will put you over $80.

 

[Let'sgoflying!]

Here, let's put the $ into perspective.
A) you let it fail and get lucky, it lasts 1000 hours. Say with labor it is $200. It is costing you $0.20 per hour.

B ) you proactively change it at 500 hours, still at $200. $0.40 per hour.

The difference in operating expense is trivial! Compare it to other expenses. (Never mind the actual number accuracy, we are looking at where the decimal is.)

40.00 per hour for gas
12.50 per hour for the average engine overhaul
00.40 for to prevent grounding, inflight control issue, possible death.

 

[ajstoner21]

Here, let's put the $ into perspective.
A) you let it fail and get lucky, it lasts 1000 hours. Say with labor it is $200. It is costing you $0.20 per hour.

B ) you proactively change it at 500 hours, still at $200. $0.40 per hour.

The difference in operating expense is trivial! Compare it to other expenses. (Never mind the actual number accuracy, we are looking at where the decimal is.)

40.00 per hour for gas
12.50 per hour for the average engine overhaul
00.40 for to prevent grounding, inflight control issue, possible death.

I see your point.

 

[gismo]

Ron has an interesting point here, that holds especially true for those that go out and spend a wad of cash on electric backups. Do those electric backups come at the cost of solid partial-panel skills? In my experience, I see more pilots spend money on fancy cockpit toys rather than establishing and maintaining solid piloting fundamentals. As a CFI-I, I wouldn't recommend an electric AI to any IFR pilot simply because if they have a good set of IFR skills, it's a piece of equipment they won't normally use even when its available.

I have a fair amount of PP practice and feel fairly competent on needle/ball/airspeed but taking off into 200-1/2 leaves very little room for any kind of mistake. And even though I've practiced it in a simulator a number of times, losing an AI, especially one that slowly rolls over shortly after breaking ground isn't something I feel comfortable with if my only backup is a T&B. That's why I have an electric AI in my panel in addition to the air powered AI and an electric T&B.

Keeping the plane right side up and headed in the right general direction without an AI, even in an airplane that will not maintain wings level on it's own isn't very difficult if you practice it once in a while but recognizing that the AI has gradually failed while leading you into a graveyard spiral and then recovering is a hole nuther kettle of crabs.

 

[timwinters]

Keeping the plane right side up and headed in the right general direction without an AI, even in an airplane that will not maintain wings level on it's own isn't very difficult if you practice it once in a while but recognizing that the AI has gradually failed while leading you into a graveyard spiral and then recovering is a hole nuther kettle of crabs.

Bingo!

Very proficient instrument pilots have perished because they didn't recognize the gradual failure of vacuum driven gyros. It's completely different than having a CFII slap a suction cup over a gyro and saying "it just failed".

I've been waiting for someone to say this.

 

[COFlyBoy]

I'm in the proactively replace group for folks regularly flying in IMC. The cost is so low that it does seem silly not to.

For VFR pilots, unless there is some vacuum pump failure mode that can damage other things, there doesn't really seem to be a good reason to proactively replace it.

Some folks were also poo-pooing the backup AIs. The FAA issued their AC on the replacement of the T&B with an electric AI. In that AC they suggested that studies had shown that the transition to the backup AI is almost a non-event whereas transition to the T&B requires regular training and practice.

I'm not suggesting that practice is bad, but I will stack the odds in my favor as much as possible. If I ever begin flying a significant amount of IMC, I will have the electric AI installed.

 

[gismo]

Bingo!

Very proficient instrument pilots have perished because they didn't recognize the gradual failure of vacuum driven gyros. It's completely different than having a CFII slap a suction cup over a gyro and saying "it just failed".

I've been waiting for someone to say this.

Of course the FAA in their infinite wisdom won't let anyone equip a trainer with the ability to simulate a real air driven gyro failure so we only get to experience this in simulators where the experience is likely much different than the real thing.

 

[ScottM]

Bingo!

Very proficient instrument pilots have perished because they didn't recognize the gradual failure of vacuum driven gyros. It's completely different than having a CFII slap a suction cup over a gyro and saying "it just failed".

I've been waiting for someone to say this.

The first time I lost the vacuum pump was in VMC. I immediately switched to m standby vac system as I was flying practice approaches at the time. But a little later I decided to switch back to the regular system to see what it was like had I not seen one of the three vacuum failure indicators in my plane. It was really eerie how the slow the AI and DG unwound. I followed it to a 40 degree bank all the while showing level on my vac instruments. It was a good experience.

BTW the new vacuum pump is on order and will be replaced next week when I am away in France.

 

[Ranger]

Vacuum pump- run to failure. I will fly hard IMC and see these go away from time to time. I have no backup electric AI, though I do have a Preciseflight Standby vacuum system.

Now I'm curious- how many IFR pilots/students here use the AI in their normal instrument scan? It's not in my normal scan. I notice a vacuum pump failure when the red light comes on or the DG stops responding. I've lost 2 vacuum pumps in IMC so far and didn't notice the AI rolling around because I just don't look at it very often.

 

[wsuffa]

Vacuum pump- run to failure. I will fly hard IMC and see these go away from time to time. I have no backup electric AI, though I do have a Preciseflight Standby vacuum system.

Then you do have a form of backup, making loss of a vacuum pump in IFR less of a factor. You do realize that PreciseFlight doesn't work well in some planes - won't deliver enough vacuum.

Now I'm curious- how many IFR pilots/students here use the AI in their normal instrument scan? It's not in my normal scan. I notice a vacuum pump failure when the red light comes on or the DG stops responding. I've lost 2 vacuum pumps in IMC so far and didn't notice the AI rolling around because I just don't look at it very often.

I do cross-checking to the other instruments. It's there for a reason. Lost an AI on a long XC flight, it was a non-issue, but it was noticed. The STec auotpilot didn't care one whit.

Personally, I prefer to keep the dispatch rate high for my plane. With business travel, downtime away from home is much more expensive than proactive replacement.

 

[David]

Good old Pesco wet pump, on its second set of vanes since 1949

I wondered was in those pumps. I just ordered a used Plessey wet vacuum pump last week for my gipsy major. I bought it as a spare but it will need to be inspected before I can use it. I hope it doesn't need any unobtanium parts

 

[Tom-D]

I wondered was in those pumps. I just ordered a used Plessey wet vacuum pump last week for my gipsy major. I bought it as a spare but it will need to be inspected before I can use it. I hope it doesn't need any unobtanium parts

The only thing that ever fails is the Quil shaft that drives it (the splinded thingy

 

[COFlyBoy]

Now I'm curious- how many IFR pilots/students here use the AI in their normal instrument scan? It's not in my normal scan. I notice a vacuum pump failure when the red light comes on or the DG stops responding. I've lost 2 vacuum pumps in IMC so far and didn't notice the AI rolling around because I just don't look at it very often.

Well going back to training (I got my IR in May), it should be a control instrument right? So anytime a deliberate attitude change is made I use the AI. When in cruise other instruments are primary.

However, this is a failure mode we are discussing. Vacuum failed, your AI and DG are slowly starting to lie to you. I'd prefer to have an electric AI to compare against, than my ball and stick. I'd really really really rather recover from a vacuum failure and an unusual attitude with a backup AI, than to try that recovery with a ball and stick.

My view:
Current on partial panel with turn coordinator = good
Current on partial panel + backup AI = waaaaay better

 

[denverpilot]

Tom or other mechanics... Why did the world move from the wet pump to dry? Seems like a step backwards in reliability.

 

[Tom-D]

Tom or other mechanics... Why did the world move from the wet pump to dry? Seems like a step backwards in reliability.

When plumbed properly they make the oil dark quickly. Remember we didn't have filtration we have today.

When plumbed to put the black oil over board they make a mess on the belly.

The dry pumps when they came out were much better quality than we see today.

 

[TMetzinger]

On the whole backup thing - I agree with the reasoning behind the FAA decision to let people replace their TC with a second AI (independently powered).

The AI gives two pieces of information in a single instrument, and allows for easy comparison between the two to detect slow failure modes. I think there's a reason that glass airplanes have backup AIs, not a TC.

I also believe that a pilot needs to be proficient with whatever backups he has. I had an AI fail in IMC and did partial-panel on the TC and the static instruments. It was ok, but not comfortable. Before the next trip we replaced the AI, and put in a backup electric AI.

Two trips later, the primary AI rolled over again. The backup AI made it practically a non-event although I missed the flight director and autopilot.

Replacing the AI again did the trick, but my takeaway was that I'd much rather have a second AI than a TC for my backup gyro.

What I REALLY like is the Trilogy - but I don't know how expensive they are. - Edit: $15 AMUs, installed. Whew!

 

[Skylane81E]

FWIW I have 1600 or so hours on my 1983 vintage vacuum pump, it's never been off the plane.

HOWEVER I consider a new pump a requirement before getting my IR.

Vac pumps can be a crapshoot, I've pulled them off with ~200 hrs jamed up solid and had others go 2K hrs. General thoughts are 500hrs is where they get sketchy and YOU need to decide the replacement interval that balances your feelings on safty vs cost.

 

[Ted]

I have wet vacuum pumps in the Aztec. One of them failed on me - it looked like it was the original one from 1969. The overhaul shop agreed. We managed to find an overhauled unit and threw it in. Had a spare, so it was a non-event.

If I were flying a single with a dry pump, I'd replace it on 500-hour intervals.

Having backups are wonderful things. The 310 has one side that's all steam and one side that's all electric (at least as much as you can get it that way). That's a wonderful setup. That way, either system that fails you have backups.

I practice partial panel regularly, and I am proficient at it. I've had actual instruments fail on me, and so I'm proficient in doing my cross-check and recognizing that. I don't care - I want backups. Just because I can do something in a degraded mode doesn't mean I should set myself up to do so.

 

[David]

The only thing that ever fails is the Quil shaft that drives it (the splinded thingy

Thanks Tom,
I'll add that to the list of items I should buy - if I can find one. I've been collecting parts, instruments, etc. since I bought the plane last year to keep as spares.
Dave

 

[Nadir]

I was taught that the DG was the primary attitude instrument. Works for me.

Same here, AI is just a sanity check. The rate at which AIs fail is quite a bit higher than DGs (at least for us). At one time both our vacuum AND electric AI failed within a couple hours of each other. Had to replace AIs in 3 out of 4 airplanes just this Spring (and did a couple the year before!). Only other type of flight instrument replaced in the past 4 years was a TC. My CFII used to "fail" the AI on nearly all my training flights. He said it'd never work anyways. He wasn't far off.

As far as the vacuum pump, we use the RAPCO. Currently got one just past 1000 hours that's nearing minimum thickness and will probably need to be replaced soon. Also had one bind up and shear the shaft off on another airplane, with only about 100 hours and 1.25 years on it (1 year warranty of course). You just never know with vacuum pumps...

 

[Nadir]

On the whole backup thing - I agree with the reasoning behind the FAA decision to let people replace their TC with a second AI (independently powered).

I can see where they're coming from with that decision since AIs are so failure prone, but I'm not a fan of *replacing* the TC with a backup AI. ADD an AI sure, but don't replace the TC. A few of us did IPCs in an airplane with only the backup AI and no TC and we all came to the same conclusion. BAD idea. Standard rate (or close to standard rate) turns were no big deal when at a level altitude, but became nearly impossible during climbs/descents as the reference marks were too far away from the bars to be able to find that 15-17 degree range! Makes for some ugly times in the ol' holding pattern when ATC has you climbing/diving!

We ordered a TC for that airplane a few weeks later and moved the backup AI elsewhere on the panel...

 

[TMetzinger]

Standard rate (or close to standard rate) turns were no big deal when at a level altitude, but became nearly impossible during climbs/descents as the reference marks were too far away from the bars to be able to find that 15-17 degree range! Makes for some ugly times in the ol' holding pattern when ATC has you climbing/diving!

I don't understand this at all. How does a climb or descent affect the indication of your bank attitude on an AI? That's what the pointer at the top of the instrument is for, isn't it? I dunno, maybe your AI looks different than what I'm used to.