thrust is approximately 29,000 pounds.
Engine Fuel System
Engine fuel system delivers the required fuel to the engine for combustion and for use by the
control system for scheduling engine variable geometry.
Engine Control System
The engine control is composed of three major components : the main fuel control (MFC),
the AB fuel control, and the digital electric engine control (DEEC). The engine has two modes of operation : primary (PRI) and secondary (SEC).
Main Fuel Control (MFC)
The MFC operates in both the PRI and SEC modes. During PRC control, the MFC receives
throttle inputs, fuel from the main fuel pump, and electrical commands from the DEEC. It
controls main ignition, start bleed strap position, main engine fuel flow, and rear compressor
variable vane (RCVV) position. In SEC, the MFC receives throttle inputs, fuel from the main fuel pump, and static pressure and total temperature signals from the fan inlet case.
Afterburner (AB) Fuel Control
During primary operation, the AB fuel control receives fuel from the AB fuel pump and electrical
commands from the DEEC. It provides AB ignition, AB segment sequencing, and fuel flow to the AB segments.
Digital Electronic Engine Control
The DEEC is the engine mounted, fuel-cooled, solid state digital full authority computer. Control
functions provided by the DEEC during PRI operation are :
Fuel flow scheduling.
Fan speed control.
Engine pressure ration scheduling.
Core compressor speed limiting.
....
The DDEC limits minimum engine rpm throughout the flight envelope to maintain stable
operation. At high altitude, low airspeed conditions, the DEEC protects against engine stalls.
During transonic and supersonic conditions, the DEEC limits the minimum idle rpm as a
function of mach number (from CADC) to provide sufficient engine airflow.
To minimize the possibility of stalls during AB operation at high altitude and low airspeed,
the DEEC commands termination of segment 11 AB.
Secondary Engine Control
The SEC is hydro-mechanical system which provides engine control in the event of a DEEC
malfunction.
Main Fuel Pump
The gearbox-mounted main fuel pump provides pressurized fuel to the MFC and boosts
pressure to AB fuel pump.
Afterburner (AB) Fuel Pump
The AB fuel pump is driven by engine bleed air and provides pressurized fuel to the AB.
Exhaust Nozzle
The exhaust nozzle is variable and consists of two sections. The divergent nozzle floats freely
and moves in conjunction with the convergent nozzle. The convergent nozzle in controlled by the
convergent exhaust nozzle control.
Convergent Exhaust Nozzle Control (CENC)
The CENC is actuated by a high-pressure bleed air motor. The nozzle schedule is controlled
the DEEC as a function of throttle input to the MFC.
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