Hydraulics Flashcards
What’s the purpose of Power
Transfer Unit?
It provides operational redundancy to left system
(especially to get the gear up with failure of left engine
on takeoff).
It’s part of both primary hydraulic systems and, when
activated, can power the flaps, landing gear, inboard
brakes and parking brakes, cabin door, and nose wheel
steering.
Ref: AOM 2A
What’s the purpose of Aux pump?
It’s primarily designed for ground and maintenance
operations. It’s part of the left hydraulic system and,
when activated, can power the flaps, landing gear,
inboard brakes and inboard parking brake, cabin door,
and nose wheel steering.
Ref: AOM 2A
Where are hydraulic reservoirs
located?
There are two (2) hydraulic reservoirs located in
forward section of tail compartment (left hydraulic
system reservoir on left and right hydraulic system
reservoir on the right).
Ref: AOM 2A
A visual sight gage is installed on
high pressure end of each
hydraulic reservoir and clearly
indicates proper FULL and
REFILL levels of the reservoir.
What is required for an accurate
reading?
Electrical power is not required to read the sight gage;
however, the system must be pressurized to obtain a
correct reading.
Ref: AOM 2A
Describe the engine-driven pump.
It’s a constant pressure, variable volume pump, which
means it produces 3000 psi anytime the engine is
running (except for a pump unloading feature during
engine start in-flight).
Ref: AOM 2A
What’s the purpose of main
hydraulic system filters and what
indication would you get for an
impending blockage?
To provide hydraulic system components with filtered
fluid. A CAS message (deactivated) for impending
blockage.
Ref: AOM 2A
What’s the purpose of hydraulic
heat exchangers and where are
they located?
There are two hydraulic heat exchangers: one for each
system located in each hopper close to the floor.
Functioning as a radiator, the heat exchanger allows
surrounding, cooler fuel to cool the hotter hydraulic
fluid.
Ref: AOM 2A
How many hydraulic accumulators
are there and what’s the pre-flight
requirement?
Two: one for each system. Check for 1200 psi at 70°F
nitrogen pre-charge on preflight.
Ref: AOM 2A
PTU’s bearing wear indicator pops
to indicate excessive motor
bearing wear. What’s the required
action if it’s discovered popped on
preflight?
Reset and note time in log book. Continued operation
for next 50 flight hours is allowed; however, you need
to check it prior to each flight.
Ref: QRH
What are the requirements for
PTU operation once it’s been
ARMED?
1) left system pressure < 2400 psi
2) fluid in left system
3) right system not hot
Ref: AOM 2A
How would the gear and flaps
operate differently with the aux
pump?
They’d operate much slower due to low flow rate
Ref: AOM 2A
What are the requirements for Aux
pump operation once it’s been
ARMED?
1) left system pressure < 1500 psi
2) fluid in left system
3) left system not hot
4) flap handle position doesn’t match flap position OR
landing gear handle position doesn’t match gear position
On ground: left system and inboard accumulator
pressure < 1500 psi and brake pedals depressed (ASC
902)
Ref: AOM 2A
How does the Aux pump operate
differently in the air when selected
to ON?
It operates regardless of hydraulic quantity or
temperature; however, it automatically shuts off after
two (2) minutes to prevent inadvertent depletion of
batteries.
Ref: AOM 2A
What can be done if the Aux pump
shuts off due to overload?
Cycle the switch and try it again
Ref: AOM 2A
There are two replenishing
systems in the tail compartment.
What are they for?
One is for hydraulics and one is for oil replenishing
Ref: AOM 2A
