Mike,
When my wife and I were preparing to close out the top inboard sections of our Legacy’s wings we had the same questions. At that time Lancair was recommending a Hysol adhesive with a surprisingly low peel strength so we looked into other options. BTW, as far as I know Lancair no longer recommends using the low peel strength formulation (forgot the ID number). My interest in the subject was peeked because there had already been a Legacy that had one of its upper inboard wing panel/skin come off in flight… It was nice, though, to know that the airplane was still able to fly in that condition and safely return to a runway.
I’m certainly not an expert on epoxy adhesives – just my thoughts on where we ended up on this.
Attached are the datasheets for Hysol 9430 and 9360 I still had from when we looked at this. The Hysol 9430 appears to have very similar properties to the 9360 -- though with different testing standards there isn’t any data showing the change in material properties at different temperatures. In talking to Hysol tech support I learned that the 9430 is a formulation for general industrial use and made by their industrial group in Connecticut. The 9360 is from Hysol’s aerospace group in California, for aerospace applications with testing to different ASTM standards than the 9430 test standards referenced. The test data in the datasheets shows the various ASTM standards used for testing and the 9360 appears to have higher fidelity testing methods called out. I only found abstracts of the standards online but what I read lead me to that conclusion.
The Lancair construction manual suggest using Hysol at high temperatures so you have a longer pot life to complete the wing closeout tasks.
I’ve heard from other builders that the peel strength of a bond using our laminating resins with flox isn’t as good as Hysol 9360. I’ve never seen any test data on our Rhino/Jeffco 1307 LV resin, though.
Another consideration that’s been pointed out to me and I’ve noticed, is that the Hysol epoxy adhesive formulations remain somewhat more flexible than our laminating epoxy resin. So when I’m deciding on a secondary bond (between two already cured parts), I think about how much flexing might be seen in the structure and joint given that the Hysol is more flexible, less brittle than the laminating resin.
Anyway, my wife and I decided to use the Hysol 9360 aerospace formulation. Can’t say it would be unsafe to use the 9430 to close out wings – though, I’d sure like to know how its performance changes across our aircraft operating temperature range. And yes, it’s blue in color where the 9430 is grey.
I think we have some epoxy experts on the LML that will hopefully weigh in on this…
Valin Thorn
Legacy Project
Boulder, Colorado
I am preparing to close a set of wings and have some questions about Hysol epoxy. I've reviewed previous posts and there hasn't been much said for awhile, perhaps because wings are coming from factory closed now.
I went to Aircraft Spruce and said "I need six quarts of Hysol." They sold me six quarts of Hysol. I used it to epoxy in a fuel drain and probe and was asked by Matthew Colliers why it wasn't blue. So, I looked closer at my manuals and saw that it calls for epoxy and flox if temperatures are below 70 degrees and Hysol 9339 if temperatures are above 70 degrees. I then went to the Lancair website and found they don't even carry Hysol 9339, but have changed to Hysol 9360. The product Aircraft Spruce sells is Hysol 9430. Lancair tech support says they don't know why 9360 is specified. "That was selected by the guy before me."
"This new and improved Hysol glue replaces the old EA-9410-2 glue. EA-9430 has the same characteristics as the EA-9410, but has a 50 minute pot life instead of the 30 minute pot life of the EA-9410 at 77°F. Used extensively in the Strojnik S2A sailplane and many other homebuilts."
Locktite tech support and the data sheets show the pot life, tensile and shear strenght to be almost identical. The one difference I can find is that the 9360 specifies shear at different temperatures while 9430 specifies the shear strenght only at 77 degrees. The guy from Locktite couldn't explain the differences, and said "they appear to be very similar products". Can anyone tell me what makes the 9360 product better suited for Lancair wings? Is there a reason not to use the six quarts of 9430 in my fridge? |
Mike Baudhuin