Fuel, Propeller, and Electrical systems

 Drawing on the left side of the brain

 Our class today had a quiz where we were supposed to draw the PT6A-67D engine in stick format. I did so, but my drawing was crude, and didn't include the exhaust pipe. I did, however, remember that the axial compressor is a 4 stage compressor and that, with 5 compressor stages and three turbine stages, the PT6A-67D has eight rotating turbines/compressors total.

The fuel system has an odd anomaly. One of the fuel pressure sensors supposedly lights when the fuel pressure drops below 10 PSI. The pump supposed to be driving that pressure only puts out 11 PSI + or - 2 PSI. It seems odd that the sensor would sense an incorrect pressure within the parameters of the pump itself. Some of my sources seem to indicate that the sensor only senses a problem when the pressure falls below 5 PSI, which would make a whole lot more sense.

And then there's the electrical system with its three buses. Complex and multi-redundant, with more than five failure modes. And each failure mode has its own annunciator indications. What fun!