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TEO-540-A1A Engine Installation and Operation Manual
Inoperative Cylinder Detection
The EECS can identify a cylinder that is not in operation. As a result, the EECS disables all spark
and fuel events for a cylinder that is non-operational.
Cylinder Head Temperature Control
The EECS monitors Cylinder Head Temperature (CHT) and corrects any cylinder temperature that
has gone above the maximum temperature limit (shown in Appendix A). The EECS keeps the CHT
below the maximum temperature limit up to the correction limit. The maximum temperature limit is
set as per the engine speed and engine load. The maximum temperature limit applies to all cylinders.
The EECS only adjusts fuel within a set range to control CHTs. The range limit prevents excessively
rich or lean operation. The EECS adjusts fuels to control the CHT with air/fuel mixtures rich of
stoichiometric. If a cylinder is currently operated as lean of stoichiometric and is hot, rather than lean
to decrease temperature, the system adjusts back to the rich side.
Turbocharger Turbine Inlet Temperature Control
The EECS only adjusts fuel within a set range to control the turbocharger turbine inlet temperature.
The range limit prevents excessively rich or lean operation. The EECS keeps the turbine inlet
temperature below a set maximum temperature up to the correction limit. The maximum turbine inlet
temperature is set in the calibration configuration.
Turbocharger Control
The EECS controls the exhaust bypass valve during engine operation. Although each channel of the
ECU can control the exhaust bypass valve actuator, only the ECU channel currently in control of the
fuel has control of the exhaust bypass valve actuator.
The EECS prevents the pressure ratio across the turbocharger compressor from going above a
maximum value set in the software.
The EECS controls the induction air manifold to a set pressure or density based on power control
position, engine speed, pressure, or density setpoint. The pressure or density setpoint is a function of
the pilot's requested power. The EECS controls the exhaust bypass valve position to the set manifold
conditions.
The EECS keeps deck pressure to a set minimum value independent of the power control position
when the turbocharger compressor bleed air is used for aircraft pressurization.
Propeller Pitch Control
The EECS automatically controls the propeller pitch of hydraulic constant-speed propellers if the
pitch is set in the software. The EECS can automatically change propeller pitch to maintain target
rpm. The EECS calculates the target rpm based on the throttle position set by the pilot. Only the
ECU channel currently in control of the fuel can control the propeller to the set position.
The engine uses the oil pressure system to adjust the propeller pitch. Oil is supplied to the governor
from the lubrication oil gallery. The propeller governor increases the oil pressure to approximately
250 to 300 psi (1724 to 2068 kPa), then adjusts the pressure as necessary to stay at the desired rpm.
The high pressure oil passes through the front main bearing and flows into the front crankshaft
gallery where it passes to the propeller pitch change system.
© 2018 Avco Corporation. All Rights Reserved
Theory of Operation
October 2018
Page 17
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