Sound Deadening Insulation

[Philpilot]

I'm in the process of renovating the interior of my 1977 Mooney M20J. I'm planning on using a flexible closed cell foam sound deadening insulation which is moisture resistant. My  problem is the following: thickness of foam, adhesive on one side or not, and foil faced or not.

 

 

[Cruiser]

snip.......

My  problem is the following: thickness of foam, adhesive on one side or not, and foil faced or not.

 

#2 Bigger problem: can you find an A/P IA to sign off on the use of this material?

 

Edit.... added addition info below

 

Has Mooney Service Bulletin M20-208B been completed on your plane? it includes new high density foam insulation and is a factory approved application.

 

PARTS LIST: KIT P/N: S.B. 208A-1

P/N ...... . DESCRIPTION .... . QTY

170018- 901 .... . INSULATION, FOAM, LH . . . 1 set

170018- 902 .... . INSULATION, FOAM, RH . . . 1 set

(Material P/N S404,

Specialty Composite Corp.)

[Alan Fox]

I have it in my E , it looks like it was fart of a kit , 3/8 thick foil backed , the bad news is they are still very loud even with the insulation , I wouldnt do it if I had to pay for it...

[Hank]

Get the thicker windshield, and a Halo headset.

[Lood]

I'm sure any FAA approved/ certified insulation material, like Soundex, or anything similar would be good to use, no?

[preinke]

I used the Soundex on my 77J. All the thickness is worked out by them and for an addition cost comes with templates for cutting out of the rolls. Mine had factory foil under the front windows so that complicated the kit a bit . It was a little thick in a couple areas with the new Plane Plastic panels and shorted one Sonalert. I had the floor foam adder and noise was significantly better than before ( no forward carpet before - A&P said it was the  unaproved kind !)

 

Paul

'77J

[Philpilot]

Thanks for all your information  In retrospect I think I'll leave well enough alone. The only area I'll change is under the hat rack ceiling where the mice used the fiberglass for nesting. Ughh 

[Piloto]

I found that the foam or other type of insulation behind the plastic panels would not help. An old friend of mine changed all the pastic panels (they were all crack) He installed thin aluminum panels covered (glued on) with carpet material. What a difference!!!. We could have a conversation in his M20E in normal voice level with no headset. I also noticed on my M20J that the noise level gets lower the more fat people you put in the plane. It appears that the body fat absorbs the noise better than the pastic panels. Which explains why my friend M20E was quieter. My theory is that the pastic panels reverberate the noise making it louder. Sound will reflect and reverberate easily from a stiff material like plastic but not from a carpet. Just do this simple test: with a pen tap on a plastic side panel and then tap on a carpet and on your belly. Which one sound?

 

To make the plane quieter I would start on the glareshield. Covering it up with carpet type material. If you like the looks you can do the same with the side panels.

 

A good cheap weekend project.

 

José

[PTK]

Jose', what do you mean by "carpet type material"?

I don't think I'm ready to cover everything up with carpet!

Is this what you mean?

I wonder if that ultrafabric like ultraleather would work as well?

[flhelo]

I bought the noise deadening insulation from LASAR. I got it on a rol. But you can get it already pre-cut at $200-$300 more. Took a decibel reading before and after, it dropped around 27 dbs. Doesn't seem like much but the passengers (girlfriend and her daughter) thought that it made a big difference.

If my plane didn't need the old insulation replaced, I probably would not have done it. But since I was going to do it, I had the seats redone and new carpet from AirTex installed. Learned a lot about what is behind all those side panels!!!

[Piloto]

Jose', what do you mean by "carpet type material"?

I don't think I'm ready to cover everything up with carpet!

Is this what you mean?

I wonder if that ultrafabric like ultraleather would work as well?

 

It does not have to be carpet material but any material that will absorbe noise and would not reverbarate.

Take a look at  http://www.audimutesoundproofing.com/audimute-sound-absorption-sheets-materials-that-absorb-sound-soundproofing-blankets.aspx for some idea. There is a bunch of websites on the subject.

 

Just don't waste your time on backside insulation because it only helps to keep your plane warm. The noise absortion material needs to be in front to be effective facing the ocupants not behind the side panels.

 

The most important to cover is the glareshield. It takes all the engine vibration and magnify it like a loud speaker. And reverberates the prop noise coming through the windshield. A good thick carpet material of your liking can easily be trimmed and glued on with silicon for easy removal or use pop rivets. If you don't do the glareshield you are waisting your time on the side panels.

 

José.

[OR75]

piloto : is that material fire resistant and approved to install on an aircraft ?

[Piloto]

piloto : is that material fire resistant and approved to install on an aircraft ?

 

Most carpets are NFPA approved. If you are in doubt you can apply fire resistant chemical such as this http://www.firezoff.com/

Most fire prone is to install insulation material  behind the side panels were electrical wire runs through. Under heavy current load the insulation reduce cooling of the wire thus reducing its rating capacity. This is why alumium sheets are installed to keep the wiring from becoming in contact with the insulation. Material attached over the panels are not subject to cause electrical fires since they are not in contact with the wires. As the NFPA code says never run an extension cord underneath a carpet.

 

José

[jlunseth]

Fire resistance is only part of the problem. Some insulation is notorious for storing moisture, and the edges of the insulation are up against the steel frame bars, so corrosion of the frame is the result. Don't ask me how I know, my aircraft was full of the stuff when I first bought it.

[OR75]

Fire resistance is only part of the problem. Some insulation is notorious for storing moisture, and the edges of the insulation are up against the steel frame bars, so corrosion of the frame is the result. Don't ask me how I know, my aircraft was full of the stuff when I first bought it.

agreed, it is very easy for water to get into very small cracks when it rains, but evaporation is very very slow in a confined space.

[jlunseth]

Yes, it can result from liquid water but the bigger problem is humidity and condensation.  Land in FL pick up some moisture, fly to altitude and if it was not water it is now.   Heck, let the plane sit around in Minneapolis in the middle of the summer and that insulation will pick up plenty of moisture.  The heavier insulation likes to keep it all.

[Piloto]

If you though carpet material traps moisture try a foam sponge type insulation material, it will drip when you squeeze it. Before installing any insulation material make sure the structure is properly coated with anticorrosion coating. I prefer marine coatings for this.

When I mentioned carpet I did not mean the shaggy type but more like the one used on floor mats. BTW carpets are used extensively on cabin cruisers and yachts to keep the Diesel engines on the lower deck noise down.

 

José 

[Marauder]

Another thing to keep in mind about flame resistant material. Depending on the treatment or material composition (how it became fire resistant), age plays a role in the current fire resistance. Just because it was flame resistant in 1975, doesn't mean it still is.

[Lood]

Yep, and lif you look at most accidents which resulted in a fire, nothing in an airplane is fire resistant, not even the aluminum. Some materials may be more reluctant to burn, but in the end, it all burns. A friend of mine experienced an in flight fire in an Ovation and he was lucky to be near a farm airstrip. He landed in time, got out unscathed and emptied his fire extinguisher, without success. The Ovation burnt out completely, except for the prop blades, one wing tip and some parts of the tail. The rest was just a heap of ash.

 

IIRC, some of the sound proofing materials are sealed in some way and cannot absorb or retain any moisture.

[Hank]

That is the difference between fire "resistant" and fire "proof."

Very few things will not burn if conditions are right--fuel, oxygen and temperature.

[triple8s]

I had to tie down until I got in a hangar and was paranoid about moisture, so......I bought an RV dehumidifier and left it in the cabin plugged in. I was amazed at how much water that thing sucked out of the air. I had to empty the water everyday until I got tired of that and modified it so I could connect a small piece of aquarium tubing so it would self drain. I ran the small hose through a small opening in the floor back by the spar infront of the rear seat and out through the belly near the step. I dont know how much the moisture would damage things in the cockpit but you'd be very suprised at how much moisture is in the air down here in the south. I also made an engine dehumidifier too and that removed lots of moisture from the engine. I discussed my primitive dryer with "Rocketman" and he made a VERY nice one. Mine was constructed out of an aquarium airpump and plastic containers, while his was constructed from water removal systems for bodyshop air compressor equipment. His is the cats meow! Would be neat to get a hygrometer connected up to the exiting air to see just how much it lowers the humidity. Would be pretty easy to put a hygrometer in the cabin. I'll never forget the little cherokee 140 that looked llike a terrarium, parked next to my Mooney one time. Thank GOODNESS I am inside now.