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Thread: PA 12 Original Gear Snubber Damage

  1. #1

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    PA 12 Original Gear Snubber Damage

    Recent annual exposed an old problem of the landing gear snubbers breaking down and hammering dents in the 1+1/4" horizontal tube that runs laterally under the bungee truss. Installed 18 extended gear a few years ago and missed the tubing damage until recently. As the tubing is cracked and requiring repair, I am looking at options. We are going to be welding in a covered aircraft and I am hoping to make the welding operation simple as I can. Obviously we will have to remove floorboards which I would love to completely replace but that appears to be near impossible without totally dismantling the boot cowl. We will section the floor boards similar to what was done with installing the 18 gear. It appears the bungee truss serves no purpose now other than supporting the original front seat, and only gets in the way of welding and properly patching the damaged tubing. Looking at the STC's for this repair and changing the front seat Ron Sullivan's SA577AL comes up, but I am having difficulty locating a current contact number to acquire this STC but so far no luck. If anybody has this information I would greatly appreciate receiving it. Also if anyone has any other ideas or STC's for addressing this truss removal and seat options I would be interested. I have explored the sliding seat options a little bit and it would be a nice feature, but I am hoping to minimize any welding that will be done inside this aircraft and keep this repair simple as possible.

    Thanks.....Rod
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  2. #2
    Steve Pierce's Avatar
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    The ones I have seen damaged were from side loads. Cut the bad section of tubing out and do a tube inside a tube repair per AC43.13.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  3. #3

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    No matter what, you need to disassemble as far as you need to I order to make the repair. You can use heat sinks either side of the weld area to protect as much as you can, but be sure you have a fire guard while welding. One of my earliest memories was my grandfather welding gear fittings on a
    ‘39 Aeronca Chief. The fuselage was uncovered, but the seats were still in it. Imagine a 5 year old kid watching Fire, Molten Metal, Sparks, and my dad telling me not to watch! Slim chance. In any case, the seat caught fire and it was a mad scramble for all the adults present to find a bucket of water to put it out! That airplane, by the ay, was the airplane I had my first flight in some months later.


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  4. #4

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    Thanks Steve, This is my damage and I am working with my mechanic to repair. Being from old school autobody I have drilled and pulled the dent and fabricated a clamp die to restore the original round shape. Then we would do a split patch repair per 43 protocol. As you can see it would be nice to clean things up to make the repair. Hence the seat mod and removal of the truss. Rod

  5. #5

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    Got the number for Ron Sullivan from Atlee Dodge. STC on the way.. Thanks dgappilot and Steve Pierce for your response. Thanks also to Atlee Dodge for the contact information....Rod

  6. #6

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    Quote Originally Posted by badmdcnman View Post
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    Thanks Steve, This is my damage and I am working with my mechanic to repair. Being from old school autobody I have drilled and pulled the dent and fabricated a clamp die to restore the original round shape. Then we would do a split patch repair per 43 protocol. As you can see it would be nice to clean things up to make the repair. Hence the seat mod and removal of the truss. Rod
    I would much prefer cutting out the old tube and do an internal sleeve repair, Figure 4-37 in AC 43.13-1b. The existing tubes are compromised, and using a dent puller on them will only make it worse. Going with a split sleeve increases the OD of the tube right where the gear stops would be changing the geometry (granted not by much). You still have those vertical tubes to contend with with your external sleeve. For me it would be easier to cut out that entire center portion removing the dented part on both sides, and run your internal sleeve the entire width and extend into the undamaged part either side.
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  7. #7
    Steve Pierce's Avatar
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    Quote Originally Posted by badmdcnman View Post
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    Thanks Steve, This is my damage and I am working with my mechanic to repair. Being from old school autobody I have drilled and pulled the dent and fabricated a clamp die to restore the original round shape. Then we would do a split patch repair per 43 protocol. As you can see it would be nice to clean things up to make the repair. Hence the seat mod and removal of the truss. Rod
    That tube is bent to far to patch. Read 43.13 on dented tubes.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers
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  8. #8
    Gordon Misch's Avatar
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    Yeah, do it "right", for sure. I had that tube break on my -12 with a hard landing. Pretty spooky - - - Repaired with sleeve, per 43.13.
    Gordon

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