Hi @Victor –
The drive file system will be FAT but the audio file extensions will be *.WAV.
Each multitrack recording is stored as a folder which includes a mono WAV for each channel you had patched to USB out when you pressed record.
You can find these folders in <USB DRIVE>:\AHSQ\USBMTK when the drive is connected to a computer.
Stereo recordings are stored as stereo WAV files in <USB DRIVE>:\AHSQ\USBREC.
If your recordings have become corrupted, they probably wouldn’t be able to be played using the SQ, but just in case they have been corrupted somehow, you can also try the steps here to recover them – https://support.allen-heath.com/hc/en-gb/articles/4402934227857-SQ-Recovery-of-corrupted-SQ-Drive-recordings
Thanks,
Keith.