Intake rubber accordion boot

[Yetti]

2 hours ago, cliffy said:

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.

There is ice door on the airbox at least on my F there is.

[N201MKTurbo]

My hangar elves had very good results that lasted years. The repair was done with black RTV and light weight fiberglass cloth. Make all repairs on the outside to reduce the likelihood of the repair getting sucked in. When they were done, you couldn’t even tell it was repaired.

If anybody is interested, I can get them to give me all the details.

[FlyboyKC]

5 hours ago, N201MKTurbo said:

My hangar elves had very good results that lasted years. The repair was done with black RTV and light weight fiberglass cloth. Make all repairs on the outside to reduce the likelihood of the repair getting sucked in. When they were done, you couldn’t even tell it was repaired.

If anybody is interested, I can get them to give me all the details.

Lasar has these back in stock. I just got mine from them from being back ordered.

 

[Shadrach]

14 hours ago, cliffy said:

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.

All Mooneys have an alternate air door. Some are cockpit controllable and some open automatically from differential pressure. 

Edited April 10, 2020 by Shadrach

[carusoam]

Alt air sources...

M20C... carb heat, is the Alt air source too...

M20R... has a magnetically closed door... and has a knob to pull to test it’s function...

Various Mooneys got different intake systems over the years... be sure to know how to operate yours... and test it to make sure it is still working...

+1 with putting the repairs on the outside of the boot... to keep parts from entering the engine...

PP thoughts only, not a mechanic...

Best regards,

-a-

[G Miller]

On 4/9/2020 at 11:58 AM, N201MKTurbo said:

My hangar elves had very good results that lasted years. The repair was done with black RTV and light weight fiberglass cloth. Make all repairs on the outside to reduce the likelihood of the repair getting sucked in. When they were done, you couldn’t even tell it was repaired.

If anybody is interested, I can get them to give me all the details.

I would be interested in the details of the repair of the intake duct.

[N201MKTurbo]

41 minutes ago, G Miller said:

I would be interested in the details of the repair of the intake duct.

Remove the duct. Scrub it with a tooth brush and Comet cleanser until it is clean in and out. Wait for it to be completely dry. 

Cut come squares and strips of 1oz plain weave fiberglass cloth. With a gloved finger, rub a very light coat of black high temp RTV over the damaged area on the outside of the boot. Make sure it is worked in well for good adhesion. Press the fiberglass into the RTV. Don’t worry about the edges of the fiberglass, you are going to trim those later, just make sure the fiberglass conforms to the shape of the boot and doesn’t have any bulges or wrinkles. Let it cure overnight. Come back the next day and trim all the fiberglass cloth that isn’t bonded to the boot. Apply some more RTV to the top of the fiberglass completely saturating the fiberglass with RTV. Use just enough to saturate the fiberglass, you don’t want any buildup of RTV. Place another layer of fiberglass cloth into the RTV and let cure overnight. The next day trim the edges of the fiberglass cloth and apply enough RTV completely cover the cloth and a bit beyond. Make it as smooth as possible. Let it cure overnight and inspect it. If it looks good an flexes OK, put it back on.

[Immelman]

Fuel tank sealant is good stuff.... stronger than RTV. Has some flex.

 

I am not a chemical or mechanical engineer, nor A&P/IA. Don't take my word for it!

Edited April 19, 2020 by Immelman

[N201MKTurbo]

21 minutes ago, Immelman said:

Fuel tank sealant is good stuff.... stronger than RTV. Has some flex.

 

I am not a chemical or mechanical engineer, nor A&P/IA. Don't take my word for it!

That would work OK too. The color won't match as well. I only tried it with RTV. I considered trying tank sealant, but it never failed after I fixed it with RTV.

And to be clear, this is an un-approved repair only fit for experimental Mooneys or in severe shortages...

[Gary0747]

I seem to recall years ago there was a process called hot vulcanizing of rubber for repairing various things.  Do any of you “old timers” recall how this worked and if anything like that exists today?

[David Lloyd]

On 4/19/2020 at 3:25 PM, N201MKTurbo said:

Remove the duct. Scrub it with a tooth brush and Comet cleanser until it is clean in and out. Wait for it to be completely dry. 

Cut come squares and strips of 1oz plain weave fiberglass cloth. With a gloved finger, rub a very light coat of black high temp RTV over the damaged area on the outside of the boot. Make sure it is worked in well for good adhesion. Press the fiberglass into the RTV. Don’t worry about the edges of the fiberglass, you are going to trim those later, just make sure the fiberglass conforms to the shape of the boot and doesn’t have any bulges or wrinkles. Let it cure overnight. Come back the next day and trim all the fiberglass cloth that isn’t bonded to the boot. Apply some more RTV to the top of the fiberglass completely saturating the fiberglass with RTV. Use just enough to saturate the fiberglass, you don’t want any buildup of RTV. Place another layer of fiberglass cloth into the RTV and let cure overnight. The next day trim the edges of the fiberglass cloth and apply enough RTV completely cover the cloth and a bit beyond. Make it as smooth as possible. Let it cure overnight and inspect it. If it looks good an flexes OK, put it back on.

I have used two pieces of thick plastic bag, put the fg cloth and RTV between, work it in and trim to size with a wheel cutter.  When ready to apply, remove one side of the plastic, put in place and remove the other plastic side, kind of like a real messy band-aid.

[carusoam]

On 4/20/2020 at 11:45 PM, Gary0747 said:

I seem to recall years ago there was a process called hot vulcanizing of rubber for repairing various things.  Do any of you “old timers” recall how this worked and if anything like that exists today?

Hot vulcanizing is a method of repairing a good rubber piece that has a hole...

Essentially put a patch over the hole... and chemically bond the new rubber to the old rubber...  vulcanization is the word used for rubber bonding reactions... aka cross linking...

 

A quick search of the internet...  There is plenty of complaints about not being available in some nanny state... but it looks like it could be bought through Alibaba for some reason...  

PP thoughts only, not a mechanic..

Best regards,

-a-

[Gary0747]

https://blairrubber.com/hot-vulcanizing-conveyor-belt-splicing/
 

maybe a business opportunity here if this kind of repair could be deemed legal given the price of new?

[G Miller]

LASAR procured one for me. I will use the old one (as near as I can tell it lasted 25 years) to experiment with repair concepts.

[carusoam]

9 hours ago, Gary0747 said:

https://blairrubber.com/hot-vulcanizing-conveyor-belt-splicing/
 

maybe a business opportunity here if this kind of repair could be deemed legal given the price of new?

Ohio is the center of rubber technology... for the US.

Goodyear tire is headquartered in Akron, OH.

Blair could be the real deal...

We need somebody to take on a rubber donut project...  

PP thoughts only, not a rubber guy... or rubber band man...

Best regards,

-a-

[outermarker]

For a 65'E it shows, P/N 41-31-38, 600115-3. What is the difference between the -3 and -005? Does anyone have photos of the differences?

[M Terry]

On 4/19/2020 at 12:25 PM, N201MKTurbo said:

Remove the duct. Scrub it with a tooth brush and Comet cleanser until it is clean in and out. Wait for it to be completely dry. 

Cut come squares and strips of 1oz plain weave fiberglass cloth. With a gloved finger, rub a very light coat of black high temp RTV over the damaged area on the outside of the boot. Make sure it is worked in well for good adhesion. Press the fiberglass into the RTV. Don’t worry about the edges of the fiberglass, you are going to trim those later, just make sure the fiberglass conforms to the shape of the boot and doesn’t have any bulges or wrinkles. Let it cure overnight. Come back the next day and trim all the fiberglass cloth that isn’t bonded to the boot. Apply some more RTV to the top of the fiberglass completely saturating the fiberglass with RTV. Use just enough to saturate the fiberglass, you don’t want any buildup of RTV. Place another layer of fiberglass cloth into the RTV and let cure overnight. The next day trim the edges of the fiberglass cloth and apply enough RTV completely cover the cloth and a bit beyond. Make it as smooth as possible. Let it cure overnight and inspect it. If it looks good an flexes OK, put it back on.

I tried this  but the RTV was still tacky a week later, and I found a new hole in the duct. Another thread suggested using a composite tank sealant instead so I re-did it with 2 layers of fiberglass and the tank sealant above and below each layer of cloth. I used cotton thread wrapping to keep the gooey fabric tucked into each of the corrugations. Seems pretty bombproof now.

I also added myself to the Lasar wait-list.

I spoke to a A&P at one of the MSCs, He said they wrap them with the self-bonding silicone tape from Spruce

[N201MKTurbo]

15 minutes ago, M Terry said:

I tried this  but the RTV was still tacky a week later, and I found a new hole in the duct. Another thread suggested using a composite tank sealant instead so I re-did it with 2 layers of fiberglass and the tank sealant above and below each layer of cloth. I used cotton thread wrapping to keep the gooey fabric tucked into each of the corrugations. Seems pretty bombproof now.

I also added myself to the Lasar wait-list.

I spoke to a A&P at one of the MSCs, He said they wrap them with the self-bonding silicone tape from Spruce

That could work. Seems like it would add too much bulk, but maybe not. 
 

I wonder why your RTV didn’t cure. I’ve never had that problem.

[EricJ]

10 hours ago, N201MKTurbo said:

I wonder why your RTV didn’t cure. I’ve never had that problem.

I'm wondering if it was too cold?   It needs Room Temperature to Vulcanize.

 

[tigers2007]

The hangar elves who refurbished mine did it without any issues. I believe they used Permatex black RTV that was fuel and oil resistant along with fiberglass cloth acquired from eBay. The job took place inside of a laundry-room at 70 degress F and was let to dry for a week or two on top of the washing machine before they remembered about the project...

A little bit of that RTV goes a long way even when you soak it into the 1" wide strips of the thin fiberglass cloth. But just like anything else, work with thin light coats that are let to fully dry before adding anymore layers.

[cliffy]

IIRC RTV requires moisture in the air to cure

A washing machine room might be a good place for the elves to work.

[tigers2007]

Interesting as when this job happened it is always around 50-60% in that room depending if there is washing going on...

[M Terry]

On 5/18/2024 at 9:55 PM, N201MKTurbo said:

That could work. Seems like it would add too much bulk, but maybe not. 
 

I wonder why your RTV didn’t cure. I’ve never had that problem.

I was a bit bulky and more resistant to flexing than the pre-repair duct. But it was completely cured the same day and I was able to squish it into place. The permatex never cured. Weeks later the smudges of the excess on the bench of my room temperature workspace are still tackey

 

[EricJ]

28 minutes ago, M Terry said:

I was a bit bulky and more resistant to flexing than the pre-repair duct. But it was completely cured the same day and I was able to squish it into place. The permatex never cured. Weeks later the smudges of the excess on the bench of my room temperature workspace are still tackey

 

It may have gotten contaminated or something, as it should cure at room temp.

[Justin Schmidt]

The first rule about hanger elves is you don't talk about hanger elves