Starting System
Right Generator Control Unit (BT002)

Location - The right generator control unit (GCU) is located above the tailcone baggage compartment.  Remove Access Panel 311EZ to access the GCU.  

NOTE: The LED fault indicators on the face of the GCU may be viewed by opening the small access door installed on Access Panel 311EZ.

View looking up at generator control units

1.  Left Generator Control Unit (BT001)
2.  Right Generator Control Unit (BT002)

Operation - The right generator control unit (GCU) is the central component in the right starting system.  The GCU contains circuits that control starter/generator voltage output, torque output (field weakening), overvoltage/overexcitation protection, automatic start cycle termination at 40% N2 speed, and protect the start system from open and short circuits.  A set of LED fault indicators is located on the face of the GCU.  If a failure is detected in the starting system, the LED's will illuminate to help identify the fault.

PINS

Functions

A

28VDC start command input from Right Start PC Board (NZ010)
J

28VDC output to left start PC board for control of the Right Start Relay (KZ008)
L

28VDC start command output to right start PC board if engine speed is less than 40% N2.
M and m

Input from Right Ground Fault  Transformers (UT006 and UZ004).
s

28VDC input from R START Circuit Breaker (CB455)
W

Variable VDC input from Right Starter/Generator (SG2) compensation windings (terminal D) for control of the field weakening circuit.
X and Y

Input from right starter generator magnetic pickup.
y

28VDC input from RH GENERATOR Circuit Breaker (HT018) for starter generator field excitation.
AA

Variable VDC output to starter generator A terminal for field winding excitation.
DD

Airframe ground input from starter generator E- terminal for GCU field winding clipping diode.
FF

Airframe ground input from starter generator E- terminal for voltage sensing.