Operation Manual Part 2

Aerosoft – Digital Aviation

CRJ-70 & CRJ-900

AOM PART 2

Systems Description

VOL

5-1-120

26-Jul-2017

Basically, the start-up process is based on bleed air to initiate the core engine start to rotate. As soon as

rotational speed is sufficient, fuel is injected in the combustion chamber and the engine gathers more speed

until it stabilizes at idle thrust. Obviously, the ignition needs to be switched on during the entire start process.

The FADEC monitors the entire start-up sequence.

Bleed air may be provided by:

• The auxiliary power unit, APU

• A ground source

• Cross bleed air from a running engine

DC power needs to be available for the starter circuits and to be transformed to AC power to supply the

ignition.

The start sequence is initiated by pressing the START switch on the ignition panel. The FADEC now opens the

starter control valve, to rotate the starter. The starter is connected via a gearbox to the second stage / N

section and increases rotational speed of the core engine. As soon as 20% N

is reached, the thrust levers are

advanced from shutoff to idle to start fuel-flow into the engine. The FADEC meanwhile enabled the ignition

and the fuel is ignited in the combustion chamber. This accelerates the engine further and after reaching

approx. 50% N

the starter cuts out and the engine is stabilized at idle by the FADEC.