Caravan PT6A-114 Prop Governor
- Thread starter lambo5oh
- Start date
Alaska45
Well-Known Member
First Post on JC for me, been a lurker for a few years. I dont have my C208 training material with me at the moment, so im going to try to remember C208 sim training...
The pneumatic governor is built into the primary prop governor unit as a safegaurd to protect the power turbine from overspeed in the event of a primary prop governor by limiting fuel flow to the flow divider. If the primary governor fails in cruise flight you will see the prop rpm redline at 1900RPM and a significant reduction of torque/gas generator rpm.
The overspeed governor is also a safegaurd to the primary prop governor and controls oil pressure to the the prop to maintain 1900 rpm in the event of a primary governor failure. The overspeed governor is checked at 1750 RPM before the first flight each day using the test switch.
It is unlikey to have see a failure of all three governors because the NF and Overspeed governors are a safegaurd to the primary governor.
So for a simple explanation to answer your question if the primary fails and then the Nf and Overspeed do not funtion, the prop and compressor rpm will exceed limits.
The pneumatic governor is built into the primary prop governor unit as a safegaurd to protect the power turbine from overspeed in the event of a primary prop governor by limiting fuel flow to the flow divider. If the primary governor fails in cruise flight you will see the prop rpm redline at 1900RPM and a significant reduction of torque/gas generator rpm.
The overspeed governor is also a safegaurd to the primary prop governor and controls oil pressure to the the prop to maintain 1900 rpm in the event of a primary governor failure. The overspeed governor is checked at 1750 RPM before the first flight each day using the test switch.
It is unlikey to have see a failure of all three governors because the NF and Overspeed governors are a safegaurd to the primary governor.
So for a simple explanation to answer your question if the primary fails and then the Nf and Overspeed do not funtion, the prop and compressor rpm will exceed limits.
SpiraMirabilis
Possible Subversive
The prop governor keeps the RPM equal or less than 1900 RPM. The overspeed governor keeps the RPM less than 1976. The Nf (fuel topping) governor keeps the RPM less than 2090 by reducing the variable Py air to the fuel control unit and dropping Ng. The last one will cycle on and off.