Vacuum pump failure or something else?

[kommers]

Yesterday, I was doing a round trip to South Carolina in my 20J and on my way back, approximately 40nm from home airport, cockpit suddenly got filled with pretty nasty odor, something like burning plastic or insulation, or burning lubricant, etc. It gave me immediate headache. At the same moment I noticed that artificial horizon glass got so foggy that I couldn't see anything on the gauge. Finally fog was gone and I noticed that the gauge failed along with heading indicator and suction gauge. For whatever reason, tower radio became very distant and barely audible although I am not sure if this is related. Well, it was light and we made it safely to home airport but I had to keep the pilot window open for the remainder of the flight since that smell would not go away. The obvious answer was that the vacuum pump failed but my mechanic said that he doesn't understand the nature of that awful smell, because, by his words, pump usually goes down silently and without causing any odor issues,nor  can he connect radio issue to the whole situation since radio sounded distant and muffled only when I was up in the air, but was perfectly ok right after we  landed. Any ideas?  Thank you for you input

[Steve65E-NC]

I have had perhaps 4 or 5 vac pump failures in fifty years and 3500 hours of flying.  Luckily never in IFR.  Never saw any smoke or other sign other than no vac.  I do have a precise flight manifold backup and understand (and have practiced with) the inverse relationship between vac and power with that system.

[1964-M20E]

Do you have an air wolf oil separator?

I had this happen in my E model no smoke but a definite odd smell in the cockpit when the vacuum pump failed.

 

I was on an IFR flight but still VFR and only 10 minuets from my departure at about 8000 for 11000.  Turned around went back to base and was able to catch my backup commercial flight. 

 

 

[N201MKTurbo]

You could have fried an autopilot pickup coil or internal lighting in the AI. It is about the only thing in there that could do that. Did your DG keep working? Do you have a fancy flight director AI? After all the vacuum source sucks air from the AI and when they fail they don't start blowing. It would have to be something in the AI or between the AI and the filter.

If the bearings in the AI went out it could generate some heat, but there is not much to outgas in there. The bearings are lubricated with a very small amount of very low volatility oil like a watch jewel oil. Not enough to make any smoke or haze.

If something caught fire near the filter it could have fogged the inside of the glass. The filter would stop the smoke, but the moisture would probably get through.

[kommers]

Directional Gyro failed at the same time... About  a week prior to this I got my GNS430 upgraded with WAAS. After the upgrade, autopilot stopped working completely. I took it back to the avionics shop, they apologized and fixed it , then tested it on the ground. I didn't turn autopilot on ever since until yesterday,  but did so while I was flying in vicinity of my destination airport in SC. The whole thing happened about 2 hours after that, on my way back to Atlanta

 

[kortopates]

Is your electrical system working normally after the event? I also would not contribute the smell and smoke to a vacuum pump failure. And would be more concerned that an electrical issue caused that and the smoke was sucked into your gyro's suggesting they will need servicing too from contamination. But I would not expect the smoke alone to cause the vacuum pump to fail either; unless some debris somehow came with the smoke and got past  the filter which seems very unlikely. Let us know what your tech finds.

Your GNS430 WAAS upgrade is surely unrelated, they just forgot to re-configure it the same way it was before the WAAS upgrade to properly talk to your AP  (each port has to be properly setup for what its communicating with such as your AP.)  Once they fixed the configuration issue it was fine.

[cbarry]

Since you mention you have a vacuum pump, I would check the filter as a sounds much like a piece of the vacuum's veins was discharged into the filter and being rather hot caused a slight singe of the filter resulting in the bad smell and clouding of the AI.  

[kommers]

Well, the preliminary report from my mechanic implicates vacuum pump alone. As to the foggy glass, I attribute it to the water condensation; I am pretty certain I saw water droplets on the internal side of glass and my wife confirms it since she was frantically scanning all the instruments when we smelled that foul odor. The smell itself is still unexplained but as I found out, the previous owner did some customization there including that Wolf air/oil separator and extra inline filter. I'll keep this thread updated as I learn more

[kortopates]

The extra filter is to protect your instruments when and if the pump fails catastrophically. Since the pump pulls air from the cabin to the pump, the smell source is most likely in the cabin. Can't imagine how your air oil separator in the engine compartment could be involved.

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