Powerplant (engine and propeller) control is achieved
by means of a power lever and a condition lever for
each engine. [Figure 14-3] There is no mixture control
and/or r.p.m. lever as found on piston engine airplanes.
On the fixed shaft constant-speed turboprop engine,
the power lever is advanced or retarded to increase or
decrease forward thrust. The power lever is also used
to provide reverse thrust. The condition lever sets the
desired engine r.p.m. within a narrow range between
that appropriate for ground operations and flight.

Powerplant instrumentation in a fixed shaft turboprop
engine typically consists of the following basic
indicator. [Figure 14-4]
• Torque or horsepower.
• ITT – interturbine temperature.
• Fuel flow.
• RPM.

Torque developed by the turbine section is measured
by a torque sensor. The torque is then reflected on a
cockpit horsepower gauge calibrated in horsepower
times 100. Interturbine temperature (ITT) is a
measurement of the combustion gas temperature
between the first and second stages of the turbine
section. The gauge is calibrated in degrees Celsius.
Propeller r.p.m. is reflected on a cockpit tachometer as
a percentage of maximum r.p.m. Normally, a vernier
indicator on the gauge dial indicates r.p.m. in 1 percent
graduations as well. The fuel flow indicator indicates
fuel flow rate in pounds per hour.

Propeller feathering in a fixed shaft constant-speed
turboprop engine is normally accomplished with the
condition lever. An engine failure in this type engine,
however, will result in a serious drag condition due to
the large power requirements of the compressor being
absorbed by the propeller. This could create a serious
airplane control problem in twin-engine airplanes
unless the failure is recognized immediately and the
affected propeller feathered. For this reason, the fixed
shaft turboprop engine is equipped with negative
torque sensing (NTS).

Figure 14-4. Powerplant instrumentation—fixed shaft turboprop engine.