PW125
I'm pretty sure that it is because when you are moving the prop , you are only connected to the power turbine at the rear of the engine, not the N1,N2 stages(compressor/turbine) of the actual powerplant. so the prop and the power turbine are interconnected on their own independant shaft.
Hope that this helps.
Last edited by tested satis; 12th Jun 2007 at 09:58.
Reason: turbine spelt incorrectly