Note that you’re not really sending hexadecimal FB C0, but are sending binary data: the bits 11111011 11000000 which for a human can be shown as FB C0, or many other formats.
To see the bits, you could use Serial.print(data[i], BIN). Of course, that’s hardly useful for humans.
Also note that in computer code it is important to be explicit.
See also Working with bytes.