AIRPLANE
OPERATIONS
MANUAL
POWERPLANT
DECEMBER 20, 2002
2-10-25
Page
1
Code
01
ENGINE ELECTRICAL SYSTEM
ELECTRICAL POWER SOURCES
Primary electrical power for engine control and the ignition system is
provided by a permanent magnet alternator (PMA) that is driven by the
engine accessory gearbox. Before the PMA attains sufficient speed to
generate electrical power, the airplane 28 V DC system is used to
power the FADEC. Aircraft 28 V DC is also used to energize a fail-safe
ignition relay, so that in the event of aircraft power loss the ignition is
turned on and the air vent valve is closed, thus preventing fuel leakage
through the vent port.
The PMA is the only source of power for the igniters. If a PMA failure
occurs there will not be any spark from the igniters.
PERMANENT MAGNET ALTERNATOR (PMA)
The PMA provides electrical power for both engine FADECs and to the
redundant ignition systems.
The PMA provides sufficient power to drive the ignition system at all
speeds above 10% N2, and powers the FADECs at a minimum of
50% N2. The PMA also provides power to the Thrust Rating Mode
Buttons, in case of electrical emergency.
For starting and emergency backup, the engine control system
requires aircraft supplied 28 V DC (GPU and/or batteries) power.
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