Starting engine with fan rotating backwards
I had not actually thought of it before. Yes I have seen the fan moving the opposite direction from the airport terminal window but it seems that it is OK that the lightoff happens even while the fan is spinning the wrong way. The N speed will be indicating, decrease to zero and then increase again.
This is for the CFM-56...not sure about other types but I have seen maximum allowable speeds for starting."
"Prior to starting, tailwinds can cause the fan to rotate in a direction
opposite to this normal operating direction.
A strong tailwind condition may result in a positive fan speed
indication prior to engine start even though the fan is rotating in a
direction opposite to the direction of normal rotation. To minimize
starter operating time, it is permitted to introduce fuel and ignition
with the fan rotating in a counter-clockwise direction.
During the engine start procedure, airflow through the core engine
will override the tailwind effect and gradually turn the fan in the
correct direction. Once the start is initiated, the fan speed indication
will decrease to zero and then increase as the fan speed increases in
the correct direction. To verify correct fan rotation, monitor the fan
speed (N1) indication prior to and during the start."