Originally Posted by
Shatwa07
Hi..
during engine start N1 was rotating by windmiling effect , are there any limit for this phenomenon to avoid any damage to the rotor shaft and the starter??
Not really. Remember that N1 is essentially a free turbine, and will start to rotate in the correct sense once the N2 has started to build up, there is a lot more force from the flow induced by the N2 than from the airflow over the N1 fan blade. The windmilling of N1 is normally in a negative direction if the wind is from the
front rear of the engine.
The starter is connected to the N2, not N1.