Cruiser Posted June 11, 2013 Report Posted June 11, 2013 How often do you run your standby vacuum system? When do you activate it? On the ground without the engine running or in flight?
Bob_Belville Posted June 11, 2013 Report Posted June 11, 2013 I got rid of mine (Precise Flight SVS-3 Stby Vac) on recommendation of avionics shop when we did panel upgrade, more trouble than it was worth with only 1 vacuum instrument plus the step retract dependent upon vacuum. But my old check list included ground check. I don't think you can check anything unless engine is running, the system uses engine intake manifold pressure differential.
Cris Posted June 11, 2013 Report Posted June 11, 2013 Check the STC attached to the POH. It should give specifics for the preflight.
Bob_Belville Posted June 11, 2013 Report Posted June 11, 2013 Tom, you may have a different system with a second pump. Mine was installed in 1997.
RJBrown Posted June 11, 2013 Report Posted June 11, 2013 I got rid of mine (Precise Flight SVS-3 Stby Vac) on recommendation of avionics shop when we did panel upgrade, more trouble than it was worth with only 1 vacuum instrument plus the step retract dependent upon vacuum. But my old check list included ground check. I don't think you can check anything unless engine is running, the system uses engine intake manifold pressure differential. This type does not use a second pump driven by a motor. It uses differential pressure in the intake system to power gyros. Engine must be running and power levels must be low. Picture #1 shows this type. NOT the most effective but the cheapest. The Aero safe system is much better it is a "real" vacuum pump driven by an electric motor. Mine sits next to the battery. This system is shown in picture #2. It can be tested with or without the engine running.
Marauder Posted June 11, 2013 Report Posted June 11, 2013 I think we need to wait for Tom to tell us what he has. I suspect it is a separate electrically driven pump on his later model Mooney. Like Bob, I dumped the Precise Flight. I can't remember the specifics but there was some sort of issue with the Precise Flight that required attention.
Marauder Posted June 11, 2013 Report Posted June 11, 2013 On the bottom of this page are the pre-flight checklist instructions for the Aero Safe: http://www.aerosafe.net/installation/
Cruiser Posted June 11, 2013 Author Report Posted June 11, 2013 I understand the procedures. I do have the electric driven pump. Just wondering what others are doing. I do not check it every time I fly. Maybe once a month or so.
Bennett Posted June 11, 2013 Report Posted June 11, 2013 I have the Aerosafe electric back-up vacuum pump. I test it every time I fly, as part of my run-up procedure. With the engine running at 1900 RPM, I test the mags, cycle the prop (usually three times), and observe all the gauges, including my vacuum gauge (this is a two inch gauge in my right side subpanel I had had installed as part of my panel rebuild). Under normal conditions at this RPM it will show exactly 5" (pointer dead center vertical on the gauge). I then flip on the back-up pump switch, and I see a jump to 5.25", and then a drop back to 5" when I switch it back off.
jeharlan Posted June 11, 2013 Report Posted June 11, 2013 I check mine before every flight and right after I turn on the master.
N201MKTurbo Posted June 11, 2013 Report Posted June 11, 2013 I have the AeroSafe system. About a month ago my vacuum pump failed on a trip to Oregon. It was VFR so I waited till I got home to fix it. I ran it for about 10 hours in two days. Even though I test it on every flight, I have never used it before. After about 10 minuets it blew its circuit breaker. I waited till my gyros spun down and then turned it on again. It lasted about 10 minuets and then blew the breaker again. I reset it one more time and then it worked perfectly for the rest of the trip. I think it should be exercised more often then turning it on for a few seconds every flight. Running it for 1/2 hour every six months would probably keep it loosened up. I'm also thinking, that next time I change vacuum pumps, I'll put the new one on the standby system and put the one from the standby system on the engine.
aviatoreb Posted June 11, 2013 Report Posted June 11, 2013 I have the electric standby vacuum pump. I check if for ~30 sec as part of preflight - before engine on - for every flight. It both confirms my stand by vacuum is working and that the vacuum instruments are working, as well as vacuum pressure guage. Then after start up I watch the vacuum instruments during vacuum and the vacuum guage as a test that the primary vacuum is working, plus I trigger my speed brakes and retract during taxi. So besides that 30 seconds per flight - I turn on the stand by vacuum on every IFR flight moments/soon before I punch into a cloud since I figure that if I need it (if my primary vacuum fails) I don't want to figure it out by my attitude indication going lazy while in the cloud - I would rather that the primary vacuum failure mode would instead be that the electric backup vacuum ends up running the gyros but I figure out that the primary vacuum has failed after I leave IMC and then I notice in VMC that my attitude indicator is lazy. I am not a hard core IMC guy and I figure maybe 5% of my flying is actually in IMC even if I file IFR maybe 75% of my cross country flying. Up and over into the sunshine whenever I can. Then descend and approach at the end whenever I can arrange it that way which does not build lots of hours on my stand by.
Awful_Charlie Posted June 12, 2013 Report Posted June 12, 2013 I have the battery one in the tailcone too. Somewhere there is a recommendation to run it once a month or similar for long enough to warm up and drive any moisture out of the motor. They are lifed at IIRC 200hrs though, so I don't run it too much, as they are a bit of a hit in the pocket to replace
RJBrown Posted June 12, 2013 Report Posted June 12, 2013 I have had 4 vacuum pump failures. 3 in N231NH all were VFR. I have had one in N1079V also VFR. The difference was in 79V I could flip a switch and have Vac again. Vac pump failure is sudden, now you have it now you don't. For safety's sake I feel MUCH better having one. I test prior to start.
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