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Thread: Nose Gear Strut Crack

  1. #1
    SWeidemann's Avatar
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    Default Nose Gear Strut Crack

    Ref: Hairline Crack in Vixen Nosegear

    I discovered what I am pretty certain is a crack outside the weld where the vertical piece is welded to the angled strut of my nose gear. It showed itself as "cracked paint", however after scraping the paint off right over the suspicious fracture, it looks like a crack. I view ANY cracks as not good. It is not a large one, but I think it will only get worse. Has anyone else had something like this show up? If so, what do you do? Is there a welded repair available, or do you replace? I suspect there may be some kind of heat treatment that won't work with welding, but maybe not?

    Any experience or ideas would be much appreciated.

    Thanks much,

    Skot
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    Kitfox Vixen 912 ULS
    N24V at C29

  2. #2
    Senior Member
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    Default Re: Nose Gear Strut Crack

    The weld bead looks very "Mig" like, which it is common to have brittle area
    like this. Likely you can take it to any good welder, and have it rewelded and
    fixed. I do a good bit of oxy/acetylene, and would not hesitate to reweld it
    myself if it were mine. Then just make it a periodic inspection item. You'd
    likely never have another problem there.

    Oxy/Acetylene, or Tig would be easy to fix this with.

    Jeff

  3. #3
    Senior Member Pilot4Life's Avatar
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    Default Re: Nose Gear Strut Crack

    "If so, what do you do?"

    Remove nose strut....install tail wheel!

    Seriously though...looks like an easy rewelding fix. Best of luck to you
    Chris Holaday
    Looking at the Model 5 or newer for size!

  4. #4
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    Default Re: Nose Gear Strut Crack

    Quote Originally Posted by Pilot4Life View Post
    "If so, what do you do?"

    Remove nose strut....install tail wheel!

    Seriously though...looks like an easy rewelding fix. Best of luck to you
    That's what I did!
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  5. #5
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    Default Re: Nose Gear Strut Crack

    I'd go to a certified welder and give his some cash to repair, an then go to a Powder Coat Paint shop give him some more cash and than reinstall and go flying .
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  6. #6
    Senior Member PapuaPilot's Avatar
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    Default Re: Nose Gear Strut Crack

    Can you think of any reason this crack has occurred? Have there been hard landings, rough strips or other things that have given the nose gear a beating? Has this happened to other nose wheel Kitfox planes?

    I wouldn't hesitate to have it welded. You could even consider adding a doubler to that area to beef it up a little.
    Phil Nelson
    A&P-IA, Maintenance Instructor
    KF 5 Outback, Cont. IO-240
    Flying since 2016

  7. #7
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    Default Re: Nose Gear Strut Crack

    If I were to talk to Bob S., Senior Fellow Materials & Metalologist Engineer he would say Hydrogen Embrittlement. Basically the welding and/or the foundry process of making high strength steels.

    The embrittlement of of metal or alloy by atomic hydrogen involves the ingress of hydrogen into a component, an event that can seriously reduce the ductility and load-bearing capacity, cause cracking and catastrophic brittle failures at stresses below the yield stress of susceptible materials. Hydrogen embrittlement occurs in a number of forms but the common features are an applied tensile stress and hydrogen dissolved in the metal.

    Examples of hydrogen embrittlement are cracking of weldments or hardened steels when exposed to conditions which inject hydrogen into the component. Presently this phenomenon is not completely understood and hydrogen embrittlement detection, in particular, seems to be one of the most difficult aspects of the problem. Hydrogen embrittlement does not affect all metallic materials equally. The most vulnerable are high-strength steels, titanium alloys and aluminum alloys.

    Sources of Hydrogen
    Sources of hydrogen causing embrittlement have been encountered in the making of steel, in processing parts, in welding, in storage or containment of hydrogen gas, and related to hydrogen as a contaminant in the environment that is often a by-product of general corrosion. It is the latter that concerns the nuclear industry. Hydrogen may be produced by corrosion reactions such as rusting, cathodic protection, and electroplating. Hydrogen may also be added to reactor coolant to remove oxygen from reactor coolant systems.
    Last edited by Paul Z; 12-27-2014 at 08:22 AM.
    Paul Zimmermann
    LSRM-A
    Garland, Texas

  8. #8
    Dave Holl's Avatar
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    Default Re: Nose Gear Strut Crack

    A very good find that's why we inspect our planes!
    As was said before has the nose gear been exposed to rough treatment? It does look like the crack formed by the weld so likley caused by hardening of the material in the weld area, I have seen this type of damage re welded successfully but as stated an area to keep an eye on in the future!
    Dave Holl
    Building Kitfox MK7
    Rotax 912ULS

  9. #9
    SWeidemann's Avatar
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    Cool Re: Nose Gear Strut Crack

    Regarding welding on the Kitfox nose gear strut, is there a concern about heat treating of the metal? The text below was copied from the Luscombe Airplanes Yahoo web forum that has technical chatter about the old certified Luscombes.

    As far as how this (Kitfox) landing gear in question was treated, I do not know since I am not the builder who put most of the time on it.

    "RE: [luscombeairplanes] LANDING GEAR WOES
    dcombs@luscombesilvaire.info08 Nov, 2006
    The gear legs are pretty highly treated (180KSI), and welding will damage the integrity. The legs must be annealed, welded , stress relieved, the re-treated and finally prepped for corrosion proofing. y the time you do all that you will meet or exceed the cost of a new or previously repaired set of legs done in a 'batch'. Classic aero inventories these in the repaired and new condition.- fully heand properly heat treated."

    Skot
    Kitfox Vixen 912 ULS
    N24V at C29

  10. #10
    WISDAN's Avatar
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    Default Re: Nose Gear Strut Crack

    Hi Skot,
    If it were me, I'd just order a new strut from John and Debra. I ordered one from them last summer and I believe it was under 500.00 dollars and fit my plane perfectly and they got the strut to me in a week or so.
    By the way my old strut was damaged by a forced landing in a very soft field.
    Dan G.
    Model IV 1200 - Tri-gear
    Jabiru 2200
    Flying

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