Unity breaks animation from Blender

Hello,
I was working on some simple animations but I have a problem with importing them to Unity. One of them has some stretch in one moment:154282-1.jpg

It seems it is scaled along some axis. It begins in 40th frame and ends in 50th. I tried different .fbx export settings but it did not help.

I found the problem which was in one keyframe, in my chest controller but I cannot describe it source because scale of the controller was all right. It was probably some kind of transformation issue + bad rig + Unity misinterpretation. Thanks for help @Hellium !

For everyone having similar problem I recommend removing keyframe after keyframe and exporting mesh to Unity to see if it helps. Have a nice day!