NLG Replacement Rubber

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JohnE
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NLG Replacement Rubber

Postby JohnE » Tue Aug 22, 2017 4:45 am

Hi Guys -

Basing this on a previous post about replacing the "pucks" in the nose gear. They eventually sag. One of the posters alluded to the source of the replacement pucks. Can someone share this with me? I believe the source of the engine mounts (DA20-A1) were sourced by Megi - a German company, they look similar. Also, the custom rig they made to compress the pucks together would be great. I chased a link that didn't exist anymore.

thanks.

John
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Re: NLG Replacement Rubber

Postby Steve » Tue Aug 22, 2017 1:32 pm

This is where I bought mine (for a DA40):

https://www.berger-tools.co.uk/Urelast__Rubber_Products/Es_Elastomer_Springs_Chloroprene_Rubber_Urelast_Shore_70_80__92/

Even with shipping from England, the cost was less than 1/3 of sourcing them from Diamond. They are standard DIN parts, just order by dimension.

Steve
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Re: NLG Replacement Rubber

Postby rwtucker » Tue Aug 22, 2017 1:38 pm

Were these pucks difficult to replace?
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Re: NLG Replacement Rubber

Postby Chris B » Tue Aug 22, 2017 5:16 pm

rwtucker wrote:Were these pucks difficult to replace?

For the DA40, the only somewhat tricky part is fabricating the clamp described by Diamond in Service Bulletin 40-082 (PDF) to compress the puck assembly. The pucks are under a fair amount of compression.

Otherwise it is straightforward.

Chris
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Re: NLG Replacement Rubber

Postby Steve » Wed Aug 23, 2017 2:42 am

Chris B wrote:
rwtucker wrote:Were these pucks difficult to replace?

For the DA40, the only somewhat tricky part is fabricating the clamp described by Diamond in Service Bulletin 40-082 (PDF) to compress the puck assembly. The pucks are under a fair amount of compression.

Otherwise it is straightforward.

Chris


Agree. I used a vise on my woodworking bench to compress, but it was sketchy. Next time I will build the clamp.

Steve
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Re: NLG Replacement Rubber

Postby JohnE » Wed Aug 23, 2017 6:28 am

Thanks for the info guys. This is on my to do list. As far as the fabrication of the tool, is this something I can make using a drill and a jigsaw? Can I source the metal from Home Depot? I know they sell the threaded rod.

I'll probably change out the pucks in a few months, so no rush. thx -John
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Re: NLG Replacement Rubber

Postby Chris B » Wed Aug 23, 2017 7:35 am

JohnE wrote:As far as the fabrication of the tool, is this something I can make using a drill and a jigsaw? Can I source the metal from Home Depot? I know they sell the threaded rod.
I don't know if the typical big-box will have 1/4" steel plate. You might check with a local metal fabricator. Steel can be a PITA, so get plenty of blades & use cutting oil.

We have a local aluminum supply shop that sells cut-offs for cheap, so I made the bases from 3/8" aluminum plate (*not* cast). One change that I would suggest is to make the end plates rectangular (instead of triangular as shown in in the service bulletin), since it will be easier to clamp the base in a vise for stability. Mine are triangular and the tool is awkward to securely hold while in use.

Chris
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Re: NLG Replacement Rubber

Postby RMarkSampson » Sun Aug 27, 2017 1:59 pm

John,
I built the jig and replaced my pucks about a year or so ago. Simple but here is are the thing I learned/recommend.

1. Use fairly rigid metal, I cannot remember the exact gauge of the steel I used but it did bow a bit when compressing the pucks. I'll probably replace my jig with thicker steel when it is time to replace my rubber pucks again.

2. Don't worry about making the jig to scale on the outside. So long as where you drill the holes are to scale it will work great. I had square pieces of metal and I did not waste time trimming them to spec per the SB. In fact, the oversized square metal make it easier to lay it on my work bench when I compressed the pucks.

3. Round any pointed edges of the metal to avoid cutting yourself, recommend good leather gloves.

4. I bought three 3-foot threaded rod which gave me plenty of extra. Two foot rod would probably have been too short. The stack of uncompressed new rubber was a couple of inches taller than the uncompressed old rubber.

5. The end of my stack was different than what the SB showed. I modified the one end of the compression jib to fit over the small base plate so it did not squeeze from on top of the two lock nuts - see picture

6. While you have the NLG off, recommend checking the bearings and large strut pivot for any excessive movement. The NLG should not wiggle side to side.
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Re: NLG Replacement Rubber

Postby Steve » Mon Aug 28, 2017 3:35 pm

RMarkSampson wrote:John,
I built the jig and replaced my pucks about a year or so ago. Simple but here is are the thing I learned/recommend.

1. Use fairly rigid metal, I cannot remember the exact gauge of the steel I used but it did bow a bit when compressing the pucks. I'll probably replace my jig with thicker steel when it is time to replace my rubber pucks again...

5. The end of my stack was different than what the SB showed. I modified the one end of the compression jib to fit over the small base plate so it did not squeeze from on top of the two lock nuts - see picture.


Thanks, Mark.

1: I am getting the materials together to build one of these jigs, as my Annual is coming up in a few months. I have bought 0.25" thick steel plate, the plans call for 5.0 mm plate (0.197"), so I'm hoping it will be thick enough. A little flex won't hurt.

5: The plans are for a jig for the DA40, not the 20, so the cutout would be different. The top of our puck stack is simply an eyebolt and nut, no plate like on yours.

Steve
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Re: NLG Replacement Rubber

Postby rwtucker » Mon Aug 28, 2017 3:58 pm

Any sense of the causes of these pucks losing dimensionality? Number of landings? Number of times the nose doesn't touch down with textbook gentleness? Environmental aging? Are the pucks in the serials without the aft CG problem being replaced sooner (confounded with the age variable)? My nosewheel has very little weight on it and, so far, the nose has not dropped.

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