Embraer EMB145 Operation Manual page 1854

GENERAL
The APU is a source of pneumatic and electrical power to be used
either simultaneously with or independent of airplane sources, while on
the ground or in flight. Basically, it is a constant-speed gas turbine
engine, consisting of a single-stage centrifugal compressor, a reverse-
flow annular combustion chamber, and a single-stage radial turbine.
The airplane may be equipped with two APU models: T-62T-40C11 or
T-62T-40C14. The Model T-62T-40C11 APU is controlled by the
Electronic Sequence Unit (ESU), while the Model T-62T-40C14 APU is
controlled by the Full Authority Digital Electronic Control (FADEC).
Both control systems provide automatic, full-authority, fuel scheduling
from start to full load operation, under all ambient conditions and
operating modes. In addition, the ESU (or FADEC) automatically
controls the APU to shut down should certain failures or events occur
during start or operation.
An automatic APU shutdown may occur either on the ground or in
flight, and takes place under the following conditions:
On the ground:
fire;
overtemperature;
overspeed;
underspeed;
failure to start;
failure to accelerate;
failure to light;
loss of speed data;
external short;
loss of ESU (or FADEC) signal;
ESU (or FADEC) failure;
bleed valve opening;
low oil pressure;
high oil temperature;
oil pressure switch short;
loss of EGT.
NOTE: In the event of fire, a 10 second delay is allowed before an
automatic APU shutdown is initiated.
REVISION 37
AIRPLANE
OPERATIONS
MANUAL
AUXILIARY
POWER UNIT
Page
2-09-05 1
Code
01