Landing Gear Bungee Replacement

13 posts in this topic

Posted (edited)

OK, I've googled my brains out and cannot come up with a supplier for the landing gear bungee shock cord.  My understanding is we use 50% stretch mil spec cord with cotton sheath and I need a black tracer for year ending in 5.

Does anyone have a supplier for the cord?  Aircraft Spruce lists shock cord in their PDF catalog, but it is absent from the website for ordering. 

Edited by Knuckledragger

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Posted

Go back to Aircraft Spruce and type in 06-12400 in the search box.  That is the part # for the 3/8" shock cord you need.  I bought one foot longer than I needed, and used that for something to hang onto when the last wrap is made and you need to tie the loop around the hook on the seat truss.  Then cut off the extra afterwards.  Jim Chuk

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Posted

And here's an old file from Steve Winder on an easy way to do the wrapping. I did 7 wraps using this length of cord.

Bungee installation.doc

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Posted

Thanks guys!

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Posted

This is so timely.  Exactly what I was thinking about today.  Onwards to Acft Spruce.

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Posted

Adding to this topic...

I just made and replaced my shock cords
...thought I should share what I went trough...

Aircraft Spruce 06-12400 is the 3/8" shock cord you need Thank you Jim for the reference!
For 7 warps you should have 90 inch between the loops Thank you Steve for dimensions and instructions! With 20 feet you will have more than you need and be comfortable, 18 feet is strict minimum as you will need a little extra to pull on when making the in loops. (Note that the tension/extension tool used will influence the amount of cord needed...)

I made a simple tool from some scrap material and spent the (very little) extra time to do something reusable rather than an quick and dirty setup for single use. After all I'll be doing this every 5 years.  Thank you http://avidflyer.wikia.com/wiki/Shock_Cord_Fabrication_and_Replacement for inspiration!  

  • Decide how much pre-tension/extension you want when wrapping the cords. I arbitrarily went for a 50% extension (20 cm relaxed, 30 cm with tension applied). Form a loop and place something to increase the friction cord to cord between the cords (I used a large rubber band...) and clamped the cords with a few cable ties.  
  • 2 additional cable ties will keep the cords together when wrapping them. Place the cable tie on your loop end before applying the tension to indicate where the limit of the wrapping - as if applying it later it might end up too close to the end of the loop.
  • A small amount of neoprene glue between the cords will increase the friction and 2 smaller separate wraps with safety wire is safer than one big...
  • To protect the metal safety wire cover the wraps with cotton band and textile glue before covering them with transparent shrink tubing.

That's it! Once you have the tool and material you can do 2 new bungees i less than 1 hour! 

How to replace the bungee cords easily is described by Steve in the Bungee installation.doc link above. 

bungee0.jpg

bungee2.jpg

bungee3.jpg

bungee7.jpg

bungee8.jpg

bungee5.jpg

bungee4.jpg

bungee6.jpg

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Posted

This Youtube Video has some advice, I wonder what our veterans say about it?  https://youtu.be/c_kEZnXDgYM

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Posted

I've changed bungees several times on Avids, the hammer handle trick doesn't work with their seat truss.  I'm almost ready to put new bungees on the Kitfox 1, so I'll get a chance to try it.  Jim Chuk

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Posted

I never found the video mentioned in the beginning of this video referring to making the bungee cords... That's why I published my post above....

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Posted

Glad you posted your info.  I ended up copying Steve's instructions this time.  Jim Chuk

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Posted

Get a set of spark plug boot pliers. Work great to hold and pull on the cord when winding it around the gear and truss. Really its a two person job. Make sure the limiter cable is not over the bungee. It can cut it off. 

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Posted

I've used the method in Steve Widners article several times to wrap mine. Still requires two people but it makes it pretty easy. The top person pretty much just feeds the cord thru the hole for you.

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Posted (edited)

A second person is the preferred option but Steve's method works well using a glue clamp. A piece of string is good help for the last wrap...

image.jpeg

Edited by FredStork

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