Embraer EMB145 - Page 1895

POWERPLANT
AIRPLANE
O
PERATIONS
MANUAL
2-10-40
Page
2
Code
01 REVISION 41
Copyright © by Embraer. Refer to cover page for details.
AOM
-
145/1114
Each FADEC receives command signals from the Control Pedestal
and from the Powerplant Control Panel and sends a command signal
to the FPMU, which meters the fuel flow to the engine in order to reach
the fan spool speed calculated by the FADEC thrust management
section.
Both FADECs alternate powerplant control. While one FADEC controls
the powerplant, the other remains in standby mode. The standby
FADEC monitors all inputs, performs all computations, and performs
built-in-test and fault detection. However, the output drivers (fuel flow
and CVG control), that command the engine, are powered off.
The active FADEC is alternated at each engine ground start in order to
minimize the probability of latent failure within the powerplant control
system/airplane interface.
The selection logic resides within the FADECs that memorize which
FADEC was used for the last engine start and commands the other
one to perform the next start, regardless of which FADEC is used in
flight.
For example: If FADEC B was used for the last start, when the pilot
actuates the next start, the selection logic will select FADEC A, as
shown in the following table:
Start In flight (alternated) Following start
FADEC A FADEC B or A FADEC B
FADEC B FADEC A or B FADEC A
Transfer from active FADEC to standby FADEC may also be
accomplished automatically, in response to a detected fault, or
manually, through the FADEC Selector Knob, located on the overhead
panel. The manual selection overrides the automatic selection of the
controlling FADEC unless the manually selected FADEC is not capable
of safely controlling the engine.
If a fault condition is detected in the engine sensor, actuator interface,
or airplane interface of the controlling FADEC, it will maintain control by
using data borrowed from the standby FADEC. If required data is not
available, the controlling FADEC will use default data or switch to
reversionary control mode.
Control will be transferred to the standby FADEC only when the
controlling FADEC detects a fault that will result in degraded engine
operation or will render it unable to control the engine.
All measured powerplant control parameters, control system faults and
status information are presented on the EICAS.