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Nose wheel spat for Jabiru


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Am I the only person who struggles with the nose wheel spat on the Jabiru J170C? Every screw holding the rear half of the spat to the front half is so tight it's impossible to get them back in. You are not able to get anything behind so you can't push hard. I have left the rear half off because it's so fu^&%$ing annoying. I'm off to Bunnings to create a better solution. 

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Went to Bunnings, no suitable taps. What I did do was file down the 'thingo' about 0.5mm and now the screws go in without a struggle. I am not convinced that the 'thingo' that the screw goes into is designed that way but everyone of them was such that getting the screws back in was impossible without filing them down. And you cannot apply any great pressure on the screws because you cannot get your hand in the spat for support. Crap design.

wheel-spat-screw-problem.jpg

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They are called "nut plates" https://en.m.wikipedia.org/wiki/Plate_nut

I've also found them tight at times. I think the threads on the end are crimped as a locking/anti vibration measure.

I usually run a tap down them.

I was advised by a bloke who built his own aircraft to use nylon washers on screws that have no positive locking measure.

Helps to prevent loosening from vibration apparently.......

Edited by Downunder
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Well, I'll add to my first flight inspection the 8 wheel spat screws - check for tightness. Normally they just get a visual. As for the name "nut plates" I have in my old age become painfully stupid in some areas, so 'thingo' had to suffice. Thanks

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9 minutes ago, tillmanr said:

Doesn’t the bolt/screw normally fit from the other side?

Yes, but the gets only part way in then becomes too tight to go any further. Filing off the end fixed the problem.

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Those nuts n screws are designed to not come loose and so have a deformed thread to make them hard to move. In the fullness of time, with lots of undoing etc, they will become easier to operate and then they will become illegal on account of how they can vibrate loose. Your plane is just too new.

I reckon those nuts are a stupid idea and you did the right thing fixing them with a file.  If you are worried about them vibrating loose ( I don't think they would ) then you could use a drop of loctite on them. If you do this, make sure its the weak loctite or you will have even more trouble undoing them.

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Perhaps a little surprisingly, either Silastic or Urethane sealant makes for a good, simple, thread lock. These products also have the advantage of sealing the threads against corrosion starting.

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WRT the Silastic comment - Silastic- as long as the chosen silicone is compatible with the metal (most neutral cures) .

 

am following... :-)

 

Bruce,  I will be in town from Dec 7 onwards. 

 

Edited by RFguy
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33 minutes ago, Bruce Tuncks said:

Those nuts n screws are designed to not come loose and so have a deformed thread to make them hard to move. In the fullness of time, with lots of undoing etc, they will become easier to operate..

The AN4 nutplates I use to secure my wing TE to the fuselage seem to have this sort of deformed thread. 
I asked the supplier how many use cycles before the treads wore out. He said hundreds: they wouldn’t wear out.

I don’t quite believe that.

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10 minutes ago, facthunter said:

I'd just clean  with a hand wire brush and apply a small amount of WD to the bolt/screw. It will usually free them enough. Nev

The screws are as clean as can be. I also tried cleaning the nut-plate. I think my solution was best. Nail polish makes a good loctite alternative. Used to use that in my video-recorder servicing days.

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Nutplates are a great fastener idea for fibreglass panels and for connecting thin pieces of material together and are especially useful when you can't get a spanner to hold or tighten the nut and you can never lose the nut as it is attached to the part you are connecting to. They don't need washers either. I have them to connect the top cowl to the bottom, on inspection covers, the spinner, spats etc. They are deliberately tight and I have removed and replaced the screws multiple times and none have ever come loose. If they are too tight a bit of light machine oil, graphite or Inox MX3 will help. If you get rid of the interference part of the thread and can tighten them by hand, replace them immediately or you will find the screw won't take long to disappear. Another option is Rivnuts but they need a bit more metal thickness & are no good on fibreglass.

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2 hours ago, Jabiru7252 said:

The screws are as clean as can be. I also tried cleaning the nut-plate. I think my solution was best. Nail polish makes a good loctite alternative. Used to use that in my video-recorder servicing days.

You could put a smear of ‘ aviation soft seal no.3’ on the threads will prevent coming loose pretty much. I use it lots on that sort of application.

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16 minutes ago, Bruce Tuncks said:

I googled that stuff up blue and liked what I saw. Is it easy to undo?

Yes.  I always have an opened bottle and an unopened nor ready for use as I use it a lot, has many uses.  I describe it’s holding like a nylock.  Nuts don’t loosen.  Bit messy so need to be careful.  Won’t go wrong buying a bottle from auto supply stores or bearing shops etc.  supercheap has it.  Cheers

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