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Thread: Loud clunk noise in left wing of PA-11?

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    Loud clunk noise in left wing of PA-11?

    Any one know what to look for to determine what is making loud clunk noise in the left wing of PA-11? I have heard it a few times while cruising. I have checked the struts and they seem fine. Is there something that can be hitting the fuel tank?

    Thanks,

    Dave

  2. #2

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    Guess i would take the tank cover off and make sure the neighbors dog isnt in there.

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    cubdriver2's Avatar
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    Did you notice if the wing is still attached or did it fall off?

    Glenn

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    royevansii's Avatar
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    How about that metal strut through the tank? Did the neighbor's dog break it?

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    Make sure the fuel cap vent is not obstructed!

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    Copilot heard it too. I'll take the cover off above the fuel tank and check the cap. Thanks.

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    At my first lesson of the third time (and yes it was the charm) that I started learning to fly my instructor, in his infinite wisdom, said "the first thing I do when walking up to the aircraft is to look for large missing parts."


    maybe look for evidence of a bird-strike
    Remember, These are the Good old Days!

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    We landed after hearing the noise, and thought it might be a bird-strike. However, we didn't see any evidence of a bird strike. I have heard it before, but without a passenger saying "what was that!". I'm going to take off some of the inspection panels and check the fuel cap today. See if there is anything obvious.

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    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by OLDCROWE View Post
    ... my instructor, in his infinite wisdom, said "the first thing I do when walking up to the aircraft is to look for large missing parts."
    I often wonder why people do preflights, I watch them do them, and like you say they would only notice something big missing....

    my other pet peeve is those clear plexi inspection panels on cubs.... do a good annual, there nothing in there that needs attention more than once a year....

    now does anyone teach the new students to bend over and wipe the crud of the gear attach fittings and see if the are about to crack off and add to you excitement and $$... no...

    we need a list of common fail items as a good/relevent preflight list???

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    www.SkupTech.com mike mcs repair's Avatar
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    worn lower lift strut attach bolt holes on fuselage? the sound radiates up strut and sounds like its up in wing.... grab wing tip AT SPARS and shake up and down with someone watching fork at bottom...

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    Roger Peterson's Avatar
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    The only two things I can think of are the gas tank oil canning and the lift strut attach points. If it is not one of those two, pull the fairing and check the spar attach points and bolts. There just ain't nothing else in there to make noise. Also ck tension on ailerion Cable. Could be a cable snapping over a broken pulley.
    Never had one make noise, but I would sure find it while on the ground.

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    My mechanic also suggested taking off the cover over the fuel tank and checking tension on the cables. He is going to look at it next week.

    He is fixing a PA-11 that went off the paved runway on a long landing and hit a couple of Cessna's tied down on the grass so he wasn't able to look at this last week. Very expensive landing... Cubs were landing on the grass along side the paved runway in the past, but some Cessna's were moved to tied downs on the grass after an event this summer and never moved back preventing use of the grass. I don't think this accident would have happened if the grass was open for use IMO, but I wasn't there.

    I just had it in for annual last month.

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    Quote Originally Posted by mike mcs repair View Post
    I often wonder why people do preflights, I watch them do them, and like you say they would only notice something big missing....

    my other pet peeve is those clear plexi inspection panels on cubs.... do a good annual, there nothing in there that needs attention more than once a year....

    now does anyone teach the new students to bend over and wipe the crud of the gear attach fittings and see if the are about to crack off and add to you excitement and $$... no...

    we need a list of common fail items as a good/relevent preflight list???
    Mike excellent point needing a list of common failures that could get caught at pre-flight... and the missing big pieces is for the walk up not the walk round/inspection and in answer to your wipe if off question yep.. I learned that way and so did Molly with a different instructor so yes in my experience there is good instruction out there.
    Remember, These are the Good old Days!

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    this would be a title NimpoCub's Avatar
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    Quote Originally Posted by OLDCROWE View Post
    Mike excellent point needing a list of common failures that could get caught at pre-flight.
    I think this is an excellent idea. Best source of "common failures" would be all you airplane fixers! It's one thing to do a preflight, quite another to know what to look for. I'm quite familiar with all my plane's parts, but don't know the common failures.

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    Couple pilots up here forgot to take wood rudder stop off, and it was fatal for both on takeoff. This could have been prevented with simple pre-flight walk around.

    Checked fuel cap and its venting. Didn't hear/see anything loose lifting up the wing under the strut attach points. Have to do the rest tomorrow.

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    On the checklist for preflight, one of the J-3 Cub guys was pining away for a checklist to read whilst aviating, and I believe one could still find his proposal in the archives. By the time he got ready to take the active, he had covered about four pages, and once lined up he had five more items to read.

    I agree - wipe the oil off those critical areas and have a look. But if you need to read something at every fitting, you will miss the crack that could hurt you.

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    mvivion's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    worn lower lift strut attach bolt holes on fuselage? the sound radiates up strut and sounds like its up in wing.... grab wing tip AT SPARS and shake up and down with someone watching fork at bottom...
    I know of a Scout that had the wrong diameter bolts in the wing strut to spar attach. If they were real snug, they might only "clunk" under a significant load like a draft in flight. That setup destroyed the front spar.

    if a wing goes "clunk" I wouldn't fly it.

    MTV

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    Alex Clark's Avatar
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    If you grab the wing tip and give it a good up and down, ( then fore and aft ) shake....do you hear the same noise ? Coming from the lift strut bolts slopping around.

    There is a big rod that goes through a tunnel which goes through the fuel tank... While super unlikely, it could have been installed incorrectly and have come loose or the tank could now be loose and banging against it... Both would require a real goof up...

    Also if your sky-light screws are becoming loose ( or the rubber washers are shot) , it will occasionally shift ( flex and pop) which will make a creepy noise.
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    It seems to only happen after hitting draft in flight. This time it was after leveling from right turn onto a right downwind for landing. It was turbulent that day. The other time I heard it I was riding a wave over/past a mountain top. I'll have my mechanic check the bolts too. I want to put in tie down brackets so might as well do this at the same time. Thanks.

    Alex - Thanks for the photo. Tank is secure. I'll leave the cover off and let my mechanic check it out this week in my hanger. Can you see the rod you are describing with the top off? The noise wasn't plastic from windows or wood from bag compartment. Definitely metal clunk.
    Last edited by DavePA11; 10-26-2013 at 01:21 PM.

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    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by Pa11flyer15h View Post
    It seems to only happen after hitting draft in flight. This time it was after leveling from right turn onto a right downwind for landing. It was turbulent that day. The other time I heard it I was riding a wave over/past a mountain top. I'll have my mechanic check the bolts too. I want to put in tie down brackets so might as well do this at the same time. Thanks.
    do you have a remote compass?? with a broken mount?

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    cubdriver2's Avatar
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    Had a noise in my vagabond wing that happened when shaking the wingtip up and down. Turned out to be the fork bolt. We put in a zero tolerance bolt and the noise stopped.

    Glenn

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    SC3CM's Avatar
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    Dave, ask the mechanic if he's missing any tools. Most of your problems seem to start after he fixes stuff. He may have left something behind

    This needs to get fixed before we do spin training!

    Rene

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    aktango58's Avatar
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    Did someone drop a plastic stick in the fuel tank when checking quantity?
    I don't know where you've been me lad, but I see you won first Prize!

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    I agree with Rene, could be a tool left behind, I had a noise in my 11 on one flight and kept looking for the source as it was just now and then, found it just before landing, after taking the last passenger flying I hadn't clipped the rear seat belts together and one was outside banging off the fabric and made a bunch of nice random cuts.

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    skywagon8a's Avatar
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    Quote Originally Posted by Pa11flyer15h View Post
    Any one know what to look for to determine what is making loud clunk noise in the left wing of PA-11? I have heard it a few times while cruising. I have checked the struts and they seem fine. Is there something that can be hitting the fuel tank?

    Thanks,

    Dave
    Does this "clunk" happen more than once per flight? If the answer is no, then I am inclined to agree with mike mcs. Though I don't understand why the hole would be elongated, other than the airplane has been mechanically abused over it's lifetime. If it only happens once, it could be that the weight of the wings, when on the ground, causes all of the slop to settle in one place. Then, when you go flying lifting the plane with the wings, the sloppy holes settle in the other direction with a "clunk". I had a Stearman which did this, never did find the source. The plane had been a crop duster/sprayer for most of it's life and had been abused.

    Loosen the nuts on the strut attach bolts, both ends. Also, possibly the wing to fuselage attachments. Then have someone lift and lower the wing at the spar tips smoothly and slowly. Don't jerk it, you might not feel the movement. While doing this place your fingers at each of the bolt connections. Your fingers are more sensitive than your eyeballs, so will feel any relative motion. The slop in a bolt hole could be very small but you will feel it, in flight, when it moves.
    N1PA

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    www.SkupTech.com mike mcs repair's Avatar
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    Quote Originally Posted by skywagon8a View Post
    ....
    Loosen the nuts on the strut attach bolts, both ends. .....
    hey, that made me think..... what about a bent/breaking upper strut attach fitting???? from being tied down to wing strut in a PAST wind storm.... he mentioned adding tiedowns..

    to check, visually look UP struts at fitting at wing it should be in line with strut, not pulled/angled down... if not in line, inspect it and make sure it's not bent.... fairly common, and you will die

    note the left strut still tied down, but that attach snapped off... this picture is of it failing, just make sure yours isn't on its way... click this for the thread & pictures #11

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    Thanks for all the suggestions. I'll check more of these out today. I haven't used a measuring stick in the tank so doubt it would be a stick. I'll check though.

    The Cub has only been baby'd so it hasn't been in any unusual conditions. I didn't let Joe or John do any loops in it. However, Glenn did ferry it over from NY to MA when I bought it, and he had a huge grin on when I saw him.

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    skywagon8a's Avatar
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    Quote Originally Posted by Pa11flyer15h View Post
    The Cub has only been baby'd so it hasn't been in any unusual conditions. I didn't let Joe or John do any loops in it. However, Glenn did ferry it over from NY to MA when I bought it, and he had a huge grin on when I saw him.
    I gather that you have recently bought it? How do you know for sure that it has only been babied? It is sixty plus years old, and likely during at least the first thirty of those, before recording tachs came upon the scene, there were lots of flights and accidents in which the records mysteriously never were recorded. Not saying that yours was one of those, just that it was common in those days. That is, unless this one was stuck in a barn in 1948 and just came out.
    N1PA

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    RaisedByWolves's Avatar
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    Quote Originally Posted by SC3CM View Post
    Dave, ask the mechanic if he's missing any tools. Most of your problems seem to start after he fixes stuff. He may have left something behind

    This needs to get fixed before we do spin training!

    Rene
    Ha.

    Dave fly down, and I'll check it out

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    Tom,

    Did you make it down to Texas? Bill and I checked out strut connections and all seem good.

    Dave

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    S2D's Avatar
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    Does it happen with a full tank or low tank?
    My first super cub would clunk after the tank got low.
    I may be wrong but that probably won't stop me from arguing about it.

  32. #32
    39-J3's Avatar
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    Quote Originally Posted by mike mcs repair View Post
    worn lower lift strut attach bolt holes on fuselage? the sound radiates up strut and sounds like its up in wing.... grab wing tip AT SPARS and shake up and down with someone watching fork at bottom...
    This is exactly the problem that I had and you would hear a bang every once in a while. We removed the lift strut bolt and forks and bushed the bolt hole on the fuselage and the problem was solved.

    Larry

  33. #33
    RaisedByWolves's Avatar
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    Quote Originally Posted by Pa11flyer15h View Post
    Tom,

    Did you make it down to Texas? Bill and I checked out strut connections and all seem good.

    Dave
    Yep. Was flying a super cub with the doors and windows open this past weekend. I'll miss skis though.

  34. #34
    cubdriver2's Avatar
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    Quote Originally Posted by RaisedByWolves View Post
    Yep. Was flying a super cub with the doors and windows open this past weekend. I'll miss skis though.
    I had the door open also. 15F this AM.

    Glenn
    Last edited by cubdriver2; 10-29-2013 at 09:11 AM.

  35. #35
    RolsCub's Avatar
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    Dave,

    Rene's suggestion of a lost tool might be right. Back in '07 when I removed the fabric from the wings of 3336N for recover. Guess what I found in the wing tip bay, an old rusty window ballance weight. I also found a ten year old mouse nest as well.


    Rollie

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    My first Aeronca had a buzz in the right wing and a patch on the bottom. When I recovered it I found about six inches of a towbar in there. jrh

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    Rolland - Did you buy that C-90 from DDM yet?

  38. #38
    RolsCub's Avatar
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    Dave, Boy he (Don Swords) does nice work, doesn't he. What I am really looking for is a 'run-out' C-90 (preferably an - with logs. The A-75-8 currently on 36N is running so good I hate to swap it out. On the other hand, I hate being Tail End Charlie when flying with you all. Hey if you need any help with your 11's noise issue let me know. I am always looking for an excuse to be at the hanger. Your hanger neighbor at 9B1. Rollie

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    Just a thought, we are redoing a 70's super cub that went on its back and after removing the 20 year old covering on the wing found a bucket full of dirt dobber (BUGS)nests,some of them loose. Many were about the size of a baseball. Not saying that's what it is, just something to look for.

  40. #40

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    So....PA-11Flyer, what was it you found?

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