I was at kualar lumpar airport last year watching the 777 that was going to take me to Perth WA, and as i looked at the fan blades they were spinning backwards. I had to look twice to make sure i was right and yep, i noted the blade orientation and they were going in reverse at about 5-6 rpm.
I had two thoughts why this were happening:
1: Wind was blowing through the back of the engine windmilling the blades backwards.
2: The pilot was running some sort of starter motor test by running it in reverse (if that is possible).
Im sure it will be the first one but i would just like to clarify it with someone who knows better.
Thankyou in advance.