737 MAX Flight Crew Operations Manual
Electrical -
Controls and Indicators
6.10.8
MN-FLT-OH-201
8
APU Generator Off Bus (GEN OFF BUS) Light
Illuminated (blue) – APU is running and not powering a bus.
9
APU Generator (GEN) Switches
Three position switch, spring–loaded to neutral.
OFF –
• APU generator powering both AC transfer buses
•moving a single APU GEN switch to OFF illuminates related
SOURCE OFF light. APU continues to power AC transfer buses
•subsequently moving other APU GEN switch to OFF disconnects APU
generator from tie bus and removes APU power from AC transfer
buses
• APU generator powering one AC transfer bus; IDG powering one AC
transfer bus
•moving related APU GEN switch to OFF disconnects APU generator
from tie bus and AC transfer bus. IDG powers AC transfer buses.
ON –
• Neither AC transfer bus powered by IDG – moving a single APU GEN
switch to ON:
•connects both AC transfer buses to the APU generator
•disconnects external power, if connected
•opposite SOURCE OFF light illuminates until the other APU GEN
switch is moved to ON.
• Both AC transfer buses powered by IDGs – moving an APU GEN
switch ON:
•powers the related AC transfer bus from the APU generator
•other AC transfer bus continues to receive power from the IDG.
Ground Service Switch
SERVICE
GROUND
FWD ATTENDANT PANEL
1
March 1, 2021
