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Intake rubber accordion boot


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5 hours ago, cliffy said:

You can do an OPP but it still has to conform FAA Approved Data for the part.

Getting the FAA Approved Data is the kicker. Either buy it from the manufacture or submit it and have it approved by the FAA

You just can't make it up. Best guess, or as good as, or better than, won't cut it. 

Secondly the part has to be made in complete compliance with the FAA Approved Data.

Change one item (polyethylene to silicone for instance) and now the part is non-conforming to the data and not legal. 

These are just 2 of the four legs of the Approved Table that have to be met for an OPP. 

I think I understand what you are saying, but the technology of the intake accordion is pretty standard.  It's essentially a specialized scat tube.  I would love to see something akin to the rubberized connectors used on turbos, etc. but I can also see that changing this essential a safety item would be a major party with the faa (thus my previous post)...

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1 hour ago, cctsurf said:

Maybe my hangar elves can work something out with these guys and a fisdo  https://www.siliconehose-china.com/custom-cold-air-intake-silicone-hose-couplers_p27.html

Custom made silicone hose couplers with whatever reinforcement you need.  SO tempting!

37 minutes ago, tigers2007 said:

Well the importation duty would be 3.1% (HTSUS 3917.39.00). Anyone have a spare that can be used as a template for the ChiCom's to look at?

I just replaced mine. The old one is in fair condition with a couple worn spots through.

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5 hours ago, cctsurf said:

Maybe my hangar elves can work something out with these guys and a fisdo  https://www.siliconehose-china.com/custom-cold-air-intake-silicone-hose-couplers_p27.html

Custom made silicone hose couplers with whatever reinforcement you need.  SO tempting!

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Easiest approval method would probably be an STC.

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  • 5 months later...
[mention=11245]tigers2007[/mention] did you ever get anywhere with this?  I know its kind of mute right now with the situation, but I thought I would ask.
Thanks!

That is a big negative due to the Wuhan Plague. No clue when the ChiCom’s will be operation again. 500k businesses have closed there. Let me reach out to her again and see where they stand. I can’t believe that Lasar has any left. Their web site has showed zero stock for months. My plane has been down for annual and it needs one.
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This is no different than the issue with new skins for Bonanza ruddervators. They're made out of "unobtainium" also. 

Items like these will be the demise of our airframes unless a solution can be found. 

Can you imagine scrapping a Mooney because an airworthy rubber duct can not be found? 

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2 hours ago, cliffy said:

Can you imagine scrapping a Mooney because an airworthy rubber duct can not be found? 

I hope we can overcome these issues.  It makes me think twice about how I will treat my current intake accordion...Not that I was being careless, but I have ideas to extend its life if my IA approves.

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Problem: Connecting two rectangles together.

  • 5" x 3" rectangle, female 1.25" deep
  • 6" x 6.75" outside rectangle (0.5" perimeter flange to Brackett filter assembly)
  • Distance between the two rectangles is 4.25" on the bottom and 7.25" on the top of the long sides of the rectangles

Why does this seem to be rocket science? @GEE-BEE ? This is getting out of control. Does this need to be a fancy accordion; is there really that much flex needed? If GeeBee crafted some out of silicone I would think that the vibration would be a non-issue. I bet @GEE-BEE could throw together some absolute haphazard rubbish and it would outlast this Aeroduct branded junk that wears through in 100 hours. @Skates97 sent me an example piece. @GEE-BEE would you be interested in this if I forwarded you the exemplar?

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3 minutes ago, EricJ said:

This is another fine candidate for an Owner Produced Part, I think.    

Rectangular object made out of aluminum with bonded and rivet clamped silicone rubber ends sounds great. BOOM! Problem solved.Maybe add two cutouts to the sides  of said box for angular entry of a supercharged ram air assist device that can be opened in clear air? Seems like its lawless out there for the time being. Anything goes!

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The problem is that the cowling is fixed, the engine is not- and it wobbles a lot on start up.  It would be a shame to ruin either the cowling aluminum or the carb air box ($$$) because this owner produced part was too stiff.

The biggest issue with the accordion design is the wire stiffener that will cut through the rubber fairly rapidly.  The steel then rusts which just makes it worse.  The question I would have for @GEE-BEE is whether or not the wire is even needed to avoid crushing caused by engine suction through the intake duct.  The unsupported distance is 2" or less.

EDIT- well, maybe 2-3" distance

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2 hours ago, Andy95W said:

The problem is that the cowling is fixed, the engine is not- and it wobbles a lot on start up.  It would be a shame to ruin either the cowling aluminum or the carb air box ($$$) because this owner produced part was too stiff.

I agree, I would not be highly comfortable with a solid center in my duct because of that wobble.  As you said, the unsupported distance is quite short.  I suppose one could go with a short support (say 1") to get the best of both worlds: support and still a fair amount of movement.  Could there be accordion folds in a rubber boot (is that what those bulbous sections in the blue boot picture basically are)?  (I'm kind of joking, but not really)...

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[mention]GEE-BEE [/mention] how difficult is it to make an “accordion” with silicone? It doesn’t have to be so eccentric like the OE design but enough to flex during startup. We all note the bulbous design in your photos but could a true accordion be formed?

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17 hours ago, Andy95W said:

The biggest issue with the accordion design is the wire stiffener that will cut through the rubber fairly rapidly.  The steel then rusts which just makes it worse.  The question I would have for @GEE-BEE is whether or not the wire is even needed to avoid crushing caused by engine suction through the intake duct.  The unsupported distance is 2" or less.

EDIT- well, maybe 2-3" distance

Who could theoretically perform a field repair on these? I'm thinking like a silicone spray gun to coat a layer over the accordion. That is probably how this is made to begin with. It looks like some sort of rubberized tape that is wrapped around a mold and is coated. I've seen some vendors that sell silicone sticky tape. Check this EZ-Spray® Silicone 20 out (video here). They claim a usable temp range of their cured product to be -65F to +500F.

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Some interesting thoughts- Field Repair?  Repairs come under either the maintenance manual (approved by the manufacturer), 43.13 (accepted by the FAA), in some cases a Structural Repair Manual and/or STCs all having some kind of approval method.

What approval method would a silicone spray system come under? Find the approved method and use it OR get the spray process approved and use it. 

Wrap with tape?  Again, approved repair method?  It all comes down to finding or getting the required approval to use the process. Find or get the approval and use it. 

Last thought- How many here have ever flown IFR and had impact icing on their air filer to the point of lowering the manifold pressure sufficiently to cause engine and flight problems? I know I have. Some Piper airplanes have a sucker door , held with a magnet, that sucks open when this happens allowing unfiltered air into the engine bypassing the air filter.  Its noticeable when it pops open.

With our design here all that lower pressure shows up behind the filter in the bellows area trying to suck the bellows down the throat of the carb.  The strength of the bellows has to account for this extreme possibility. The design of the bellows or any repair has to preclude any part of it from coming loose and being sucked into the venturi of the carb and shutting off the engine. Just look to the ADs on the old way Brackett had for their filter gasket or the AD on the old paper filters that came apart or even the AD on the carb venturi coming apart and blocking the throat of the carb.  Just random thoughts on what is a complicated process on a seemingly simple problem.

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1 hour ago, tigers2007 said:

Who could theoretically perform a field repair on these? I'm thinking like a silicone spray gun to coat a layer over the accordion. That is probably how this is made to begin with. It looks like some sort of rubberized tape that is wrapped around a mold and is coated. I've seen some vendors that sell silicone sticky tape. Check this EZ-Spray® Silicone 20 out (video here). They claim a usable temp range of their cured product to be -65F to +500F.

The risk is that the pressure drop on the air box side sucks the silicone through. Many a pilot as tried to RTV these things. Mixed results at best.

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