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S-1207 Spinner Pitot Bushing

mwardle7

Well Known Member
I can't seem to get Loctite 243 to hold the spinner pitot bushing in place over the long term. This is what the manual suggests, and it doesn't work well for me. Anyone else having this problem, or have found a better solution:

Also, does anyone know what material the bushing is made out of?
 
I can't seem to get Loctite 243 to hold the spinner pitot bushing in place over the long term. This is what the manual suggests, and it doesn't work well for me. Anyone else having this problem, or have found a better solution:

Also, does anyone know what material the bushing is made out of?

Mine came loose at 400hrs and I used pro-seal to reaffix it, that was only 25hrs ago but I think it'll hold.
 
Loctite thread locker only cures between metal fasteners where it is not exposed to air (anaerobic). It will not cure when used between plastic parts.
 
Mine departed somewhere around 200-ish hours. I don't know what the original builder used to secure it, but I used Proseal on the replacement.


BTW... I am just baffled by the recommendation to use blue Loctite. I'm sure there is some reason someone came up with that, but I can't imagine what it might be. It just seems like about the last thing you'd want to use for that application. Loctite does make some adhesives that would probably work fine, but 242 or 243 aren't among them.
 
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Was surprised to find my bushing came off during the first week or so of testing ... I too had used blue Loctite as suggested in the plans.

Ordered a new bushing and installed it using a thin coating of Pro-Seal on it and made a thin bead on the backside with a syringe ... so far all is well. Actually found the one that flew off a week or so later ... seemingly unscathed. So now I have a spare.
 
Mine came off also, we used 243 to attach it the first time but now its epoxied and holding strong.
 
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Loctite 7649/7471 primer/activator

1. According to the various downloadable Loctite user guides, most Loctite threadsealing products, such as Loctite 222 and 243, must be used with Loctite 7649 or Loctite 7471 primer/activator on inactive surfaces. The only active surfaces listed are brass, copper, bronze, or iron. Inactive surfaces are aluminium, stainless steel, etc., and obviously include our spinner and its bushing, both being non-metallic.
2. A primer/activator is also required when the thread gap to be sealed or locked is large, a relative dimension, but one that I think would apply to the bushing/spinner gap.
3. A primer/activator can be used when temperatures are very low to speed up the process.
Assuming that Loctite 243 has been used successfully to bond the bushing into the spinner, or it wouldn't be in the KAI, my question is, 'have any bushings fallen out despite using a primer/ activator?'
 
Data point: I installed the pitot bushing in 5/2013 using "blue Loctite" per Van's plans. Four years and 600 flight hours later the bushing is doing very well with no sign of loosening.
 
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The loctite was originally specified because it was something that was needed during the engine installation, and it would be needed for maintaining the engine in the future.

It works well if the fit of the busing is the desired level of clearance with the hole diam. that is specified, but apparently that can vary more than desired and some people have had them come loose, so the new plans for the iS airplane will be specifying using tank sealant.

It is fairly viscous so does a good job of gap filling if needed, and because it is flexible it will assure that differences in expansion/contraction will not be a factor (if there is a chance that that also was, but that is unknown).
 
Thanks Scott, you always do a great job of clarifying the thinking behind so many aspects of the build that have us builders perplexed.
 
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