Operation Manual Part 2

Aerosoft – Digital Aviation
CRJ-70 & CRJ-900
AOM PART 2
Systems Description
VOL
5
5-1-74
26-Jul-2017
HYDRAULIC POWER
The CRJ has three hydraulic systems. Systems 1 and 2 are identical. All three systems operate on a nominal
pressure of 3,000 PSI. Each system has two pumps. A main pump (A) for normal power and a backup pump (B).
System 1 and 2’s main pumps are engine driven pumps (EDP). The backup-pumps are AC-motor pumps
(ACMP). Pump 1A is driven by the left engine, while pump 2A is driven by the right engine.
System 3 has two AC motor pumps. Pump A runs continuously whereas pump B is only running when high
flows of hydraulic are required. In case supply of AC fails, pump 3B may be supplied by the ADG.
Except pump 3A all pumps have three operation-Modes:
• ON
• AUTO
• OFF
In AUTO mode, the pumps will start running automatically under the following conditions:
• AC BUS 2 must be powered for pump 2B operation
• AC BUS 1 must be powered for pump 1B operation
• Flaps are out if the 0° position
In case of an engine fire the engine-driven pump of the affected engine needs to be shut off with the engine
being shut off. Hence a shut-off valve is installed for pumps 1A and 2A to shut them off as well as son as the
fire handle for the engine is pulled. Closing this shut-off valve can also be done manually.