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11 Answers

My Vacuum pump field on C172S G1000, am I legal for VFR flight?

Asked by: 15924 views FAA Regulations

While taxing to the active RWY the annunciator turned on "LOW VAC" and the Vacuum pump indicator show Zero. Is that going to affect the PFD?

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11 Answers



  1. Kris Kortokrax on Aug 11, 2013

    If you have a pilot certificate, then there are several disturbing things about your questions.

    You seem not to be familiar with 91.205 regarding required equipment.

    You seem not to be familiar with 91.213 regarding inoperative equipment.

    You don’t appear to be familiar with the G1000 equipment in the airplane you are flying and the fact that it derives its information from the AHRS, ADC and Magnetometer to display flight instrument information on the PFD.

    You don’t appear to be aware that the vacuum system is supplying information to the standby attitude indicator.

    You don’t appear to be familiar with the Kinds of Operations list in the C172S POH which would tell you whether or not the vacuum system is required equipment for VFR flight.

    If you don’t have a pilot certificate, the above combined references contain the answers to your questions.

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  2. Sam Dawson on Aug 11, 2013

    What Kris is saying is go to 91.213 and follow the procedure. He is being snarky about it because you really should have been taught this in your primary training but unfortunately this is often not the case.

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  3. Mark Kolber on Aug 12, 2013

    Sam, that’s to be expected. There’s waaay too much time spent on memorizing stupid mnemonics about burning red fruit and doing nasty things to felines instead of teaching a 91.213(d) analysis.

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  4. Sam Dawson on Aug 12, 2013

    Mark, I agree and encounter it almost monthly. My classic was a PA34-200T owner and a flight school CP telling me a turbo charger could be inoperative as it was not in TOMATOFLAMES.

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  5. Mark Kolber on Aug 12, 2013

    That’s really common, Sam.

    Periodically, I used to put a very simple airworthiness question on an online forum – stall warning inop; can you fly?

    Answers always included, “yes because it’s not in T…F.”

    What got me is that even CFIs were guilty. It was usually well down in the answers before someone mentioned the true starting point: 91.213.

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  6. Kris Kortokrax on Aug 12, 2013

    There was no “snarkiness” implied in my post. It is simply a statement of facts based upon the poster’s questions. I expressed my thought that it is disturbing that a pilot would fly an airplane without being familiar with the information listed. It is also disturbing that an instructor would recommend someone for a practical test who doesn’t know this information. It is also disturbing that a Designated Pilot Examiner was unable to detect an obvious deficiency during the practical test.

    I cannot control inferences taken, but there is no malice contained in my post.

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  7. Bruce J. Sato CFI, CFII on Aug 13, 2013

    In the PFD you have an attitude indicator and a heading indicator, above the throttle and mixture knobs you see a Standby attitude indicator.

    Attitude Indicator
    *Data on the attitude indicator located on the PFD is shown by the GRS77 (AHRS)
    *The GRS77 is a unit that contains 3 rate sensors, 3 accelerometers, and 2 axis tilt sensors for position data.
    *The 3 combined replace the conventional gyros like the one found in the standby indicator.
    *Its a gyro but instead of mechanical stuff it has lasers and sensors that make up a gyro.
    * The data is then taken to the GIA63
    *GIA 63 is the brain of the system, there are 2 of them for redundancy just in case one fails the other kicks right in.
    *They contain a GPS receiver, VHF navigation receiver, VHF communication receiver, and the main system micro-processors.
    * Lastly the get displayed on the PFD and MFD

    Heading Indicator
    *Also found on the PFD but is a little different from the attitude indicator
    *Data on the heading indicator is provided by the GRS77 and GMU44 (Magnetometer)
    *The GMU44 (Magnetometer) is a unit that is located inside the left wing and does the work for the magnetic compass but instead has a digital output of the correct heading.
    *The GMU44 interacts with the GRS77 to provide the heading information.
    *The GRS77 and GMU44 computer units are located behind the baggage compartment.
    * The data is then taken to the GIA63 for processing.

    Now that you know how they work on the G1000, you noticed that they are mainly computers.
    The vacuum pump is there to power the gyros in the standby attitude indicator, just incase the one of the 2 GIA63’s, GRS77, or GMU44 fail.

    Now for your situation the vacuum indicator showed on the MFD that it had no vacuum, I think the indicator was working right IMHO, and that it showed the “LOW VAC” that only happens when the system senses less than 3.5in

    Perhaps you had the engine on idle for a while and you herd a chime come on, along with a red low vac annunciator, and a yellow highlighted vacuum indicator? increase the throttle to 1,000rpm to have sufficient vacuum, it is engine driven.

    Was there a flag on the standby indicator?

    Remember in aviation we do for a reason, regs are there to help you be safe.
    So read the regs and try to fully understand them, if you have any questions ask your instructor they are there to help you, at least most of them are I hope.

    Good luck hope this helps

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  8. Ami on Aug 16, 2013

    Kris, I could not find anything related to The POH or FAR 91.205 can you please provide with reference.

    Thanks

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  9. JohnBurns on Aug 16, 2013

    Kris, that was an incredibly rude response and only discourages people from asking questions.

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  10. Ami on Aug 16, 2013

    Hey Kris, Here is a copy from the POH. If you read it carefully you will find that the Vacuum System support only the Standby Instruments (arterial horizon) no connection to the AHRS, ADC and Magnetometer like you say

    ACUUM SYSTEM AND INSTRUMENTS
    The vacuum system, Refer to Figure 7-9, provides the vacuum
    necessary to operate the standby attitude indicator. The system
    consists of one engine-driven vacuum pump, a vacuum regulator, the
    standby attitude indicator, a vacuum system air filter, and a vacuum
    transducer. The vacuum transducer provides a signal to the engine
    display that is processed and displayed as vacuum on the EIS ENGINE
    page. If available vacuum, from the engine-driven vacuum pump, drops
    below 3.5 in.hg., the LOW VACUUM annunciator will display in amber
    on the PFD.

    ATTITUDE INDICATOR
    The standby attitude indicator is a vacuum-powered gyroscopic
    instrument, found on the center instrument panel below the MFD. The
    attitude indicator includes a low-vacuum warning flag (GYRO) that
    comes into view when the vacuum is below the level necessary for
    reliable gyroscope operation.

    VACUUM INDICATOR
    The vacuum indicator is incorporated on the EIS ENGINE page, found
    along the left side of the PFD during engine start or the left edge of the
    MFD during normal operation. During reversionary operation, the EIS
    bar appears along the left side of the operational display.

    LOW VACUUM ANNUNCIATION
    A low vacuum condition is annunciated along the right side of the PFD
    by a amber LOW VACUUM annunciator.

    Also, KINDS OF OPERATIONS EQUIPMENT LIST for VFR Day/Night don’t require Vacuum Pump

    FAR 91. 205 OMLY FOR IFR required Vacuum Pump

    So I really don’t know how you came up with your arrogance answer you almost fooled all of as.

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  11. Mark Kolber on Aug 17, 2013

    Kris, I could not find anything related to The POH or FAR 91.205 can you please provide with reference.

    then…

    [discussion of what you found] So I really don’t know how you came up with your arrogance answer you almost fooled all of as.

    Ah, but Ami, notice how the result was that you got into the POH to find the answers to every comment he made and answered almost all of your own question. Maybe not the most-appreciated use of language, but a heck of a good teaching moment.

    Still one more step, though. Your ultimate question is whether, given all that you can fly. And that requires a 91.213(d) analysis.

    +5 Votes Thumb up 6 Votes Thumb down 1 Votes


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