I did it by the "hard way": (first if its possible clone this disk before you do anything!)
dmesg for the raid-disk or try (example: sdc1)
$ fdisk -l
Change the RAID-DISK-Flag to your Linux filesystem (ext3 or something), save this and reboot.
$ mdadm --zero-superblock /dev/sdx
and voila you can mount
$ mount /dev/sdc1 /mnt