Lost vacuum on way to Florida IFR in VMC

Lkrautheim

Lkrautheim

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Lkrautheim
First time for me but a lot of good lessons learned.

We left Pennsylvania on 11/26 at 8:30 AM, I was 30 miles north of St Simons Island, our second stop before Daytona. I got the red light and the VAC annunciator on the panel. I looked at the Vac gauge and there was no vacuum. Now, what to do? As I watched the AH tumble and see the glass get foggy along with the DG start to do wired things I realized I had an issue.
I have a Precise flight standby vacuum but never needed it. I pulled the cable out and was surprised to see that nothing had changed! I pushed it back in and pulled it out several times watching the DG and the AH as well as the Vac gauge but nothing! Now what? I had already disengaged the autopilot as I started to evaluate the rest of the airplane. Engine ran smooth, all other gauges were normal and the wife was asleep in the back with he 2 dogs.

My thoughts were to land and check things out but the plane was flying fine. I was assuming the Vac. pump went south. Since I was VMC and DAB was only 45 more minute flight, I would continue on. I asked approach to activate my final leg to DAB and I continued, hand flying of course and using the 396 and iPad as reference.

About half way to DAB the AH righted itself, but not level. The DG seemed to stop its procession but was slow to move. I reset the DG to the Wiskey compass and it seemed to be working, but slowly. I advised DAB approach of the situation and ask for small changes in direction and no ground assistance was needed. The landing and taxi was uneventful and when inside the FBO I advised the mechanic of my issue. (more to follow on the cause)

I wanted to share my experience in hopes to educate other pilots if faced with a similar scenario and I'm sure there will many to critique my decision to continue on.

Some key points I would like to share and these are my personal opinions only.

1) Understand your emergency back up systems and exercise them regularly. You should know what will work and what will not work when faced with a problem.
2) iPads are great but, to “many gadgets” are a distraction. Also, iPads battery life is not the best and, when faced with extending your flight, and your battery is almost dead, it only adds to the distraction.
3) Standby systems should be checked as part of an annual inspection
4) If you have a 12 volt receptacle that you use for charging, make sure your charger does not interfere with radio transmission and or reception, (mine did)

Lenny K
Piper Lance
N575DC
 
That sound like a vacuum pressure regulator sticking. That would explain that you still had no vacuum when you shifted to alternate. Vibration can unstick such devices, at least partially, and the gyros come back up, partly or completely.

A cracked vacuum line, leaking in air, could also cause such indications.

I hope the mechanics find the problem quickly, and have the parts you need.

Not sarcastically, Have a great Thanksgiving, you are fortunate to have such a small problem.
 
My Precise Flight installation had an informative placard regarding RPM range required for it to work as I recall (no MP gauge in that installation)


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Lkrautheim said:
1) Understand your emergency back up systems and exercise them regularly. You should know what will work and what will not work when faced with a problem.
....
3) Standby systems should be checked as part of an annual inspection
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IIRC, there’s a pre-takeoff check for your standby vacuum system, in addition to the power chart that @Bill Watson mentioned.
 
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Here’s a good question for the hive mind. What is the cost difference in installing an alternate vacuum source vs. the avionics to make the vacuum irrelevant (a couple G5’s, for example)?
 
Vacuum failure in VMC? No reason to not press on to your destination in my opinion.

Small issue in the big picture. One that shouldn't interfere with the ability for your bird to land you and your family safely.

If this was IMC, or if your destination was IMC, other decisions may have been prudent.
 
The differential MP alt vac systems have vacuum production limitations, and are around $600 plus installation, which is a good down payment on one or two G5s. There are no limitations on the G5 AI if the main power fails. The HSI will lose the magnetometer info, but should still otherwise function.

In VMC vac failure is mostly a non-event. It's a little more urgent when IMC. I'm not missing my vac system with the new G5s. Indeed, I gained a few pounds of useful load.
 
Let me guess; you had a "modern" dry vacuum pump. I will never understand why the FAA permitted these as they are very short lived and are almost certain to fail unless you replace every few hundred hours. Wet, engine oil lubricated, pumps are extremely reliable. You can buy them rebuilt outright for under $700 last time I looked .Since you will not need to remove before engine TBO the savings in labor cost will pay for them.
 
I’m done with my 3rd instrument lesson, next one we’re supposed to do partial panel. CFI says loss of vac in single pilot IMC, declare an emergency. I have the Precise Flight standby vacuum system, but didn’t think of it to discuss with him until this post.
 
455 Bravo Uniform said:
I’m done with my 3rd instrument lesson, next one we’re supposed to do partial panel. CFI says loss of vac in single pilot IMC, declare an emergency. I have the Precise Flight standby vacuum system, but didn’t think of it to discuss with him until this post.
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You’ll probably want to review the Supplement with him so you’re both sure about proper preflight procedure and inflight use/capability. That’d make for some really good oral fodder IMO.

Obviously there can be other reasons for loss of vacuum, so partial panel is still your backup, so you’ll want to be proficient at it.
 
Rgbeard said:
Vacuum failure in VMC? No reason to not press on to your destination in my opinion.

Small issue in the big picture. One that shouldn't interfere with the ability for your bird to land you and your family safely.

If this was IMC, or if your destination was IMC, other decisions may have been prudent.
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Agree with your assessment... I wish I had a better understanding of the standby vacuum system. Immediate activation of standby system and reducing power should have given me a partial reading on the vacuum gauge and if so, and in IMC, land immediately..
 
455 Bravo Uniform said:
I’m done with my 3rd instrument lesson, next one we’re supposed to do partial panel. CFI says loss of vac in single pilot IMC, declare an emergency. I have the Precise Flight standby vacuum system, but didn’t think of it to discuss with him until this post.[/QUOTE
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Snowmass said:
Let me guess; you had a "modern" dry vacuum pump. I will never understand why the FAA permitted these as they are very short lived and are almost certain to fail unless you replace every few hundred hours. Wet, engine oil lubricated, pumps are extremely reliable. You can buy them rebuilt outright for under $700 last time I looked .Since you will not need to remove before engine TBO the savings in labor cost will pay for them.
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I’ll look into that.. thanks
 
455 Bravo Uniform said:
I’m done with my 3rd instrument lesson, next one we’re supposed to do partial panel. CFI says loss of vac in single pilot IMC, declare an emergency. I have the Precise Flight standby vacuum system, but didn’t think of it to discuss with him until this post.
Click to expand...
Read and understand how it works and actually use the system so you know what to expect. Just don’t go through the motions thinking you know..
 
MauleSkinner said:
You’ll probably want to review the Supplement with him so you’re both sure about proper preflight procedure and inflight use/capability. That’d make for some really good oral fodder IMO.
Click to expand...

That there. Part of the requirements of the STC is a flight manual supplement and a panel decal, and the pilot should know how to use the system.
 
Snowmass said:
Let me guess; you had a "modern" dry vacuum pump. I will never understand why the FAA permitted these as they are very short lived and are almost certain to fail unless you replace every few hundred hours. Wet, engine oil lubricated, pumps are extremely reliable. You can buy them rebuilt outright for under $700 last time I looked .Since you will not need to remove before engine TBO the savings in labor cost will pay for them.
Click to expand...

Wet pumps are messy things. Really messy. Even with an air/oil separator they blow oil all down the airplane's belly. I wouldn't mind that so much, but a lot of guys hate a dirty underside. That oil also creeps into the belly through the lap seams and once inside it attracts whatever dust gets in there and creates a horrible, sticky, sludgy mess.

The dry pumps, depending on the installation, run just fine. People just expect them to last forever, that's all. Continental vac pump drives spin faster than Lycomings, so they'll wear out pumps faster. Dry pumps get hot, too, so the Rapco cooling shield can help them last longer. All pumps have a plastic coupling to save the engine's accessory drive gears if the pump seizes, and that plastic coupling deteriorates in the heat and oil and gets old, so the manuacturers typically put a six-year life limit on it. I can tell you that plenty of dry pumps fail just because that coupling is old, and probably plenty of wet pumps quit that way too.

It's the vane wear in the pump that fails it. And now there's NO excuse to run a pump until it quits. Both Rapco and Tempest have vane-checking methods for their pumps, and you do the first check at 500 hours or so and every 100 hours after that, until the indication shows the vanes at at the wear limit, and you replace the pump. It can be done at annual and takes a whole five minutes or less. Why anyone would buy an Airborne pump with no such means of checking is beyond me. No wet pump that I know of has that, either, and they do still have carbon vanes that wear out.

A dry pump will last a long time if it's kept cool, and you can run it to its economical limit with the vane check. And keep the vacuum central and relief valve filters in good condition. Too often I've found the relief valve filter all decayed and fallen off. Pretty poor annual inspections those airplanes are getting. Older relief valves (vacuum regulators) had just screens on them. Not good. Contaminants going into the pump aren't helping things. And if it does blow up, all the lines all the way back to the instruments should be cleaned out. Those instrument cases act as vacuum reservoirs that suck carbon debris back up into the system when the pump suddenly fails, and if you just replace the pump it could suck that junk into itself right away and cause damage that shortens its life, and the owner then blames the pump as being cheap and short-lived. Read the installation instructions. Grrr.

If the pump broke when you turned the propeller backwards, thank your lucky stars it didn't fail in flight at night or in IMC. Only badly worn vanes will do that.
 
Lkrautheim said:
Read and understand how it works and actually use the system so you know what to expect. Just don’t go through the motions thinking you know..
Click to expand...

I’m a VFR pilot, I would never have used it until now anyway. Have owned the plane for about 2.5 yrs. I read the instructions earlier today based on this thread. Will test it next time I fly.
 
Does your EFB have an AI view? I added the AHRS to my Stratux and tried it on a partial panel approach with safety pilot. It was very usable.


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Issue with the vacuum system was due to the pump coupling.
 

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Dan Thomas said:
Wet pumps are messy things. Really messy
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Not nearly as messy as the fatal crashes that result due to vacuum pump failure. Dry pumps are junk. Wet pumps are virtually indestructible; they will outlast your engine. And wet pumps are much cheaper not only because they last much longer but you also avoid the labor to keep replacing which can really add up before TBO.
 
The best solution is to simply get rid of the vac pump altogether and install more reliable electronic instruments. Mechanical gyros also have a significant failure rate. I've been through quite a few vacuum AIs and DGs over the years. With dual G5s a lot would have to go wrong to lose both units. And you still will have a mechanical turn coordinator as a third backup as long as you have ship's power. The G5s have their own power in case of power loss.

Flying partial panel (typically using the turn coordinator, as vacuum instrument failure is the most common fault mode) is not that hard. It's the leadup as the vacuum instruments slowly fail and provide conflicting information that you have to recognize and sort out. It is weird when VFR, but could be quite a handful while IFR in IMC.
 
The club I just joined put a 750 and two G5's in. Makes me feel a whole lot better than the vacuum pump and a backup that to my knowledge was never inspected and confirmed working in my old club plane. With the G5s, if everything went hooters up they will run on their own backup batteries for 4 hours. And if you had he worst luck in history and lost your electrical system and the AI G5, the DG G5 can be switched over to AI mode. I don't think there is a plausible scenario akin to partial panel with this setup.
 
mryan75 said:
The club I just joined put a 750 and two G5's in. Makes me feel a whole lot better than the vacuum pump and a backup that to my knowledge was never inspected and confirmed
working in my old club plane. With the G5s, if everything went hooters up they will run on their own backup batteries for 4 hours. And if you had he worst luck in history and lost your electrical system and the AI G5, the DG G5 can be switched over to AI mode. I don't think there is a plausible scenario akin to partial panel with this setup.
Click to expand...

Even better, if the G5 AI totally crumps, just power it off (if it hasn't already) and the HSI will AUTOMATICALLY switch to AI mode for you. That's a nifty feature.
 
mryan75 said:
The club I just joined put a 750 and two G5's in. Makes me feel a whole lot better than the vacuum pump and a backup that to my knowledge was never inspected and confirmed working in my old club plane.
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There should have been a preflight/pretakeoff check for the backup system.
 
I think flying partial panel in imc. not pretend ifr in clear weather is not easy. You may have a turn coordinator but no direct pitch instrument. On my IPC this year the CFI disabled the vac and therefore AI when I was turning to intercept the ILS. I didn't do well that first time and it would have been awful in real imc in the air. You have no direct way of stopping a turn since you have no direct image of wings level only the result of it. I did better,ok the second time when he failed it while I was already on the ILS and mostly wings level, slight pitch down.
 
Lkrautheim said:
I would continue on. I asked approach to activate my final leg to DAB and I continued
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In addition to the required reports in AIM 5-5-3 this note applies:

NOTE

−

1. Other equipment installed in an aircraft may effectively
impair safety and/or the ability to operate under IFR. If
such equipment (e.g., airborne weather radar) malfunc-
tions and in the pilot’s judgment either safety or IFR
capabilities are affected, reports should be made as above

The post implies that the OP continued operating IFR (while in VMC) and he states he did not notify ATC until approaching DAB.

Would you have notified ATC sooner than the OP did?
Would you have notified DAB approach?
Does it matter that he thought it would affect his terminal operations but not his enroute?


 
Dan Thomas said:
Ok. Quote the statistics that prove that.
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Isn't this a rather silly request. Has an airplane ever crashed because of oil on the belly? Has an airplane ever crashed because of vacuum pump failure? What do you think? However, I recently read of a plane that crashed in Illinois due vacuum failure. I think it was an AOPA article on safety on the web but I do not keep records of what I read.
 
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chemgeek said:
The best solution is to simply get rid of the vac pump altogether and install more reliable electronic instruments. Mechanical gyros also have a significant failure rate.
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While electronic may be more reliable (and expensive) that does not make then safer. Vacuum gyros will almost always give warning well before total failure via bearing noise or drift and you then can replace that gyro before total failure. After all how does something as simple as an air jet blowing against buckets on the gyro wheel fail except by bearing failure? When electronics fail there is usually no advance warning, it's the nature of electronics.
 
Snowmass said:
Isn't this a rather silly request. Has an airplane ever crashed because of oil on the belly? Has an airplane ever crashed because of vacuum pump failure? What do you think? However, I recently read of a plane that crashed in Illinois due vacuum failure. I think it was an AOPA article on safety on the web but I do not keep records of what I read.
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No. I want statistics. Your contention that a wet pump is safer than a dry pump is based on personal bias and the folklore pilots gossip about, not experience or hard data. You look after your own private airplane; I and a bunch of other guys here are or were full-time career mechanics and/or pilots. That wet pump has no means of checking vane wear and so there is no way to determine what life is left in it, as opposed to the Rapco or Tempest vane wear indicators. Further, it still has a plastic drive coupling that ages and fails, and so many pumps are run until that happens. It doesn't matter whether the pump is wet or dry; an aged-out coupling still fails it.

As a director of maintenance I looked after a fleet of airplanes in a flight school for 11 years. I bought Rapco pumps, checked them as per Rapco recommendations, and never had a single pump failure. Not one. The fleet ran between six and eight airplanes and most accumulated between 400 and 800 hours per year, each. All but one had a full vacuum system driven by a dry pump. The fleet would have flown at least 30,000 hours in the time I maintained it, and NOT ONE PUMP FAILURE in that time. The key is to know where that pump's wear is at. In a flight school the plastic drive never gets to 6 years.

Cessna's requirement is to either replace that pump every 500 hours, or install the vane-wear-indicator type. And yet people still run them until they fail. Even wet pumps. Go figure. Would they do that with their engines???

I had an IFR ticket, too, and had to demonstrate partial-panel IFR approaches. I taught IFR as an instructor for a short time as well. Crashes due to pump failure are due either to a lack of maintenance or a lack of proficiency, exactly the same way crashes happen in any other conditions.

We often hear on this forum that one should never turn the prop backwards or you'll break the vacuum pump. That advice arises out of the fact that the angled pump vanes will not tolerate being turned backward when they're worn far past the wear limit. And that advice is a result of pumps breaking when people turned the prop backward, proof that they're not maintaining stuff to a safe standard. An engine will often kick backward when starting is difficult, so the engine and everything attached to it has to be able to tolerate that.
 
If you want statistics then go look for them. I am sure they will bare me out. As an aero engineer it's pretty obvious that an oil lubricated steel is far more durable than than a dry fragile carbon vane. My wet vacuum system came from the factory with sharp right angle ells but dry pumps require sweep ells. There is no way to check wet vane wear because it is not necessary because they are so durable.
 
Snowmass said:
If you want statistics then go look for them. I am sure they will bare me out. As an aero engineer it's pretty obvious that an oil lubricated steel is far more durable than than a dry fragile carbon vane. My wet vacuum system came from the factory with sharp right angle ells but dry pumps require sweep ells. There is no way to check wet vane wear because it is not necessary because they are so durable.
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Strange. I find right angle ells on factory installations of dry pumps. Maybe you'd better call Cessna and correct them.

NO machine is so durable that there is no need for maintenance or periodic replacement to avoid failure. None. Any engineer would know that.

Dry pumps are used in aircraft with air-powered deice boots. Can't have oil in that. The input and output of the pump are both plumbed to a cycling valve that alternates vacuum and pressure on the boot to break the ice away. Dry pumps are also used in airplanes with high service ceilings; at high altitudes it's difficult to get enough pressure differential with vacuum to drive the instruments, so the pump's output is used to drive the instruments. Air is run though a filter and then pushed into the air ports of the instruments and it leaves via the vacuum ports. Again, a wet pump would wreck those instruments in short order.
 
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Give up. Dry pumps are crap and everybody that has any experience with both knows. Cessna says check or replace at 500 hours. But when Cessna had wet pumps there was never mention of replacing at any time because they all went to engine TBO at which time they would need to come off.
 
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