2 part epoxy for aircraft components

[Higgler]

We are assembling an antenna for use on miliatry Jet aircraft need recommendations on a 2 part epoxy that is used to fill in part of the antenna.

In discussions with a co-worker, I've mentioned factors listed below for the choice of the epoxy, such as:
1) room temp cure is convenient in manufacture
2) coefficient of expansion should match the housing
3) resistance to jet fuel and hydraulic fluid is nice
4) toxic fumes when the material burns aren't good
5) ease of re-work may be a factor.

The specific question is;
a) can anyone recommend a two part epoxy for this use
b) what performance criteria is important for this epoxy.

Thanks,
kch (antenna engineer)

 

[CoryPad]

Go to these sites and use their web facilities:

3M -

http://selector.3m.com/selector/us/...gineered_adhesives/surface/ss.asp?FAM=surface

Loctite -

http://www.loctite.com/int_henkel/loctite_us/index.cfm?&pageid=19&layout=3

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[Higgler]

Thanks Cory,
My reasoning for the question was to find out if there is a high of level of concern by Engineers for materials used in aircraft, specifically regarding noxious fumes when burned and their resistance to chemicals (JP-#, Hydraulic fluid), which is something I'm not to familiar with.
These items don't have high visibility in the websites, especially the noxious fumes. I fear choosing/recommending materials that after 30 months of testing a military customer may inform me that the material is aero-non-grata and force me to change to the standard approved material that everyone knows about.
Is there a rule of thumb for materials that are used in aircraft construction, such as ?X-type rubber, type Z? foam, type Y epoxy, etc? Is there an approved materials list anywhere?
kch

 

[USACompositeGuy]

Are you working on interior or exterior components? I would guess that you are working interior and that is why you are concerned with smoke? I am sure that I could give you some guidance but I need a little more information on what you are working on.

http://www.carbonfibersolutions.com

 

[Higgler]

It's for external antennas typically.
Years ago I was involved in specifying materials that went into electronics inside a military aircraft and they were very concerned how the materials burned, and that they not create noxious fumes for the pilot and crew.
We use epoxy to bond alot of materials together in our antennas. I was curious if anyone had experience with different epoxies used in aircraft components. Or am I overly concerned with the makeup of the epoxy I choose in regard to noxious fumes.
Thanks,
kch

 

[SuperStress]

Toxic smoke is generally not a concern for things like antennae mountings.

Two decent epoxies I've worked with are 3M 3501 and 3M 2216.

These are pretty standard aerospace structural adhesives that have been approved for use many times.

Good Luck.

SuperStress

 

[Higgler]

Thanks Superstress,

Kevin.

 

[pterodactyl]

Hi Higgler,

If you want to minimize outgassing, match thermal expansion, and be re-workable you might consider a silicone material. There are several RTVs that we use for aerospace components - there is a 3145 that I believe conforms to MIL-24624...

But if you need a structural potting material there are several very rigid materials available - Dow Corning is the manufacturer of choice in my line of work - "Stycast" 2652 is a particular fave.

Epoxies are typically stiff and may embrittle or crack if they are exposed to temperature extremes. I would recommend the silicone approach if you do not need structural support but need to keep an environmental seal across a broad range of operating temperatures. Epoxies are also sometimes very aggressive during their curing and will shrink and cause damage to fine wires that pass out of the potting.

Cheers