Hi Steve
Wow I`m sorry about your loss!
Flutter can happen with slop and loose servo gears so,this is what I think happend
The 9650 not a good choice for Ailerons they are known for center slop even on elevator half use.
Ive seen stripped gear from bumping them getting in and out of a car.
The gear train on these are very weak, so I`m sure it`s where your problem started
once again Sorry

I talk about this on my website in the owners set up instructions servo- linkage to the ailerons are very important
the ailerons on this airplane are large and can flutter with broken servo or linkage
Steve
let me know if I can help you in any way
Bryan