Thanks for all your help, especially Luap and flyNfrank. This is great.
I have retracted the last six files from that particular day (May 8) by their respective numbers. I thought the last file (fly068) should be the crash file, but, since flyNfrank mentioned, that I should upload the largest file (which is fly065 - 300MB), so I moved six files to dropbox. I hope the crash-file is among them. Otherwise I would have to connect to the drone again and see whether there are more files from that day. You can find the files here:
Fly063.dat (1,8MB):
Dropbox - FLY063.DAT
Fly064.dat (90MB):
Dropbox - FLY064.DAT
Fly065.dat (300MB):
Dropbox - FLY065.DAT
Fly066.dat (6MB):
Dropbox - FLY066.DAT
Fly067.dat (58MB):
Dropbox - FLY067.DAT
Fly068.dat (43MB):
Dropbox - FLY068.DAT