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weight on wheels (WOW) signals in per-
forming it’s analysis.
In the event the DEEC fails to maintain engine
rpm within limits, a mechanical flyweight
governor, within the fuel control unit (Figure
7-16), provides overspeed protection by op-
erating the metering valve to restrict fuel flow
and keep the engine from exceeding 105% N2
rpm. Should the governor fail to limit the en-
gine speed, the DEEC will energize the ulti-
mate overspeed solenoid valve closed at 107%
N1 or 109% N2 to shut off fuel flow to the en-
gine (Figure 7-16).
If computer-on engine control is not satisfac-
tory, the engine can be operated in the man-
ual mode. The manual mode can be selected
by placing the ENG CMPTR switch to either
MAN or OFF. If the L/R ENG CMPTR switch
is placed in the MAN position, the manual
mode solenoid is deenergized closed, the en-
gine fuel control is in the manual mode and the
DEEC is no longer controlling the engine.
However, if electrical power is still available
to the DEEC and the computer switch is in
MAN, it still monitors N1 and N2, and can pro-
vide engine overspeed protection by energiz-
ing the ultimate overspeed solenoid closed if
N1 reaches 107% or N2 reaches 109%.
If the L/R CMPTR switch is placed to OFF, or
electrical power to the computer is lost, op-
eration is the same as with the switch in man-
ual, but the ultimate overspeed protection is
no longer available.
The DEEC has an extensive self-monitor and
fault analysis system. In the event a minor
fault is detected in the system, the DEEC will
initiate a “L/R ENG CMPTR FAULT” message
on the CAS. The white “L or R ENG CMPTR
FAULT” CAS will only illuminate on the
ground to indicate a minor computer fault.
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
7-19
FOR TRAINING PURPOSES ONLY
FlightSafety
international
429 DATALINK
MACH, ALTITUDE, TAMB, PAMB
THRUST SET
TORQUE MOTOR
ELECTRICAL SIGNAL
FUEL IN
IDLE
T/O
MCR
APR
MCT
CUTOFF
IGNITION RELAY
N2
N1
ITT
SURGE VALVE
TT2
PT2
AIR DATA
COMPUTER
MANUAL CONTROL
DIGITAL
ELECTRONIC
ENGINE CONTROL
(DEEC)
Figure 7-14. DEEC Inputs and Outputs