Why do turining on the generator increases the prop RPM ?[Answered]

[aymerickb426]

Hello, one simple question regarding an engine behavior that really surprised me:

After an engine startup, with prop lever full, it doesn't reach the full RPM unless we turn on the generator.

If we turn on the generator, the RPM increases by like 200.

If we turn off the generator, the RPM decreases by the same amount.

What is the logic behind this ?

Thanks

[Slayer]

I'm not 100% certain but I believe the generators need to be above a certain RPM to function properly. I believe there is other reasons why but you would probably have to research it.

[Taguilo]

Hi,

That is a realistic behavior.

When N1 is in Idle (62%) and there is no Generator/GPU power available (28V), the props are on the FLight Low Pitch Stop (FLPS) position. Once 28V power is available (by either GEN or GPU active), pitch stop decreases to Ground Low Pitch Stop (GLPS) position, therefore increasing prop base RMPs from ~ 900 to ~ 1100. At that moment the advisory white message "L/R PROP PITCH" is displayed on the Pedestal Annunciator.
GLPS is used on the ground to improve taxi speed control while maintaining above minimum prop RPMs.


Tomas

[aymerickb426]

Thank you guys for the explaination. You rock. Awesome product.