Smoke?

Discussion in 'Maintenance Bay' started by 4RNB, Feb 20, 2021.

  1. 4RNB

    4RNB Pre-takeoff checklist

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    Background
    1. I am ignorant ish 70+ hr student, airplane owner.
    2. Oil changed recently.
    3. Com 1 was all static today, unusable.
    4. 1974 C172 M

    I think I am getting close to checkride time for private. Today was supposed to be last mock checkride with CFI, get signature to test. I'm flying in to meet him, overfly the field, hear winds are 8G17, sock is erect, perpendicular to field. I am signed off for XW of 10, decide to come home. Immediately get a puff of grayish smoke in cockpit, I think electrical smell. Did not last long. I turned for RW right away, added flaps, slipped, 40 flaps, smooth landing. Trust me, I did not notice any winds...

    Mechanic to help troubleshoot. Did not fly it further.
    Where would you look? What is the seek and find algorithm for this?
    How and where does air come in from at bottom of windshield? Might it have been a drop of oil near a hot intake?

    What would you do?
     
  2. Dana

    Dana Pattern Altitude

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    First thing is to look under the instrument panel and cowl for anything awry. Then turn on switches and look again. Then do it with the engine running (vibration).

    Above because you said "electrical smell" and radio unusable. Otherwise I'd suspect spilled oil smoking off... but that would likely be right away, not after flight to another airport.
     
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  3. unsafervguy

    unsafervguy Pattern Altitude

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    first question, was it oil or electrical. they have two distinct smells.
     
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  4. Ravioli

    Ravioli Ejection Handle Pulled PoA Supporter

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    Okay... so you're signed off for XW of 10. You said 8G17. Why didn't you attempt to land? (17-8)/2 = gust factor of 2.5 which is right at your XW limit IF the Gust was maxed and actually 100% XW. So, perhaps broke off too soon, could have done an attempt, go around, etc.

    Best news is you didn't start a checkride. Less paper and money, unless your DPE is going to charge you for the no show.

    Next step? Don't diagnose anything yourself. Lay off the internet (we don't know **** about the actual situation).

    Get ready to write some checks.

    Report back on the outcome.
     
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  5. 4RNB

    4RNB Pre-takeoff checklist

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  6. 4RNB

    4RNB Pre-takeoff checklist

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    Interesting.

    Former owner just called. He commented on a few things.

    1. Pull radios and smell them.
    2. Check light ballasts as they are notorious for going bad. Check interior lights and rheostats.
    3. Leave NAV light switch on. Turning it on and off cycles the NAV lights to solid vs flashing. When flashing they caused COM1 interference. Of note, a very experienced pilot thought he noted COM1 problems on a BQ1 flight we took last month. Perhaps it was flashing today and interference multiplied to radio frying?
     
  7. Ravioli

    Ravioli Ejection Handle Pulled PoA Supporter

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    Sounds like @4RNB needs to read up on crosswinds. 10kts XW is the the crosswind component. You didn't specify the wind direction or runway orientation. You could have 75K winds right down the runway and be Zero crosswind, right?

    Er. re-reading it you said xw-wind. Okay, you were really close to your allowed number, and with gusts over it. But you also said you were going to meet your CFI. He must have known what you were heading into.

    Sounds like you did the safest thing and your obviously alive to talk to about it. But do review what it all means as you review the event with CFI.
     
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  8. Let'sgoflying!

    Let'sgoflying! Touchdown! Greaser! PoA Supporter

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    After a diagnosis is not reached* and you go flying again, have a solid plan for the next time, including when the smoke is worse.
    (*it often is not)
     
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  9. Jdm

    Jdm Pre-takeoff checklist

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    Nice job Captain! You’re on the ground safely. No one should second guess your emergency authority. I sure as hell won’t.
    Now about that smoke. How about let’s not fly this airplane again until a licensed mechanic verifies the malfunction and the corrective action. If the oil was changed and the residual not cleaned with a proper engine wash it could give off a hint of smell. I doubt it would give off actual smoke in the cockpit. As someone previously mentioned, the back side of the instrument panel would be a top priority in troubleshooting.
     
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  10. 4RNB

    4RNB Pre-takeoff checklist

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    Examination suggest bad prop seal. Will degrease and run up Monday to confirm.
     
  11. Magman

    Magman Pre-takeoff checklist

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    I doubt if the smell came from a Prop Seal.

    Droplets on w/s is typical.

    I had this happen to me once.

    Thought it might be a toasted diode or such.

    Never did find the issue.

    I have wondered if it may have been from something I flew over.
     
  12. 4RNB

    4RNB Pre-takeoff checklist

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    IMG-1023.jpg IMG-1024.jpg
     

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  13. Magman

    Magman Pre-takeoff checklist

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    Is the Seal still there?

    Looks like you found the culprit.
     
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  14. 4RNB

    4RNB Pre-takeoff checklist

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    We never pulled the prop off.
    The mechanic did a ground run up yesterday, no more oil was found.
    Today we (myself and a new to me CFI) ran the plane around on the ground for a while, then up to 4000 ft and then 8000 ft for some circles around the airport. 1.9 hours.
    Com1 worked well, no static.
    No oil out of the engine that we could tell.
    No smoke.
    No electrical smell.

    For now, considering it a gremlin.
     
  15. Daleandee

    Daleandee Cleared for Takeoff

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    I had a trace of smoke once when my oil breather tube connection came loose on a previous plane I owned.

    It was just a whisper of smoke I saw but it made me practice getting down and out real quick! :D
     
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