HYDRAULICS
Description
Aircraft Operations Manual
10.1
PAGE
2
Aprr 01/15
2.3
Hand pump selector
As the hand pump does not have the capacity to
simultaneously operate all systems, a selector valve
is installed. The valve allows pressure to be di-
rected to the following accumulators, one at a time:
−
Main accumulator.
−
Outboard brake accumulator.
−
Inboard brake accumulator.
To extend/retract the flaps, the flaps handle must
first be set to desired setting before using the hand
pump to extend/retract the flaps to selected setting.
To extend the landing gear, the handle must first be
selected down before using the handpump to ex-
tend the gear.
2.4
Hydraulic accumulators
The four identical accumulators are of piston
−
type
and are precharged with nitrogen to 1650 psi. Each
accumulator has a capacity of 22 cubic inches
(approx 0.35 liters) hydraulic fluid at 2900 psi pres-
sure.
It is important to notice that, in case of a hydraulic
pump failure, when pressure is consumed and pres-
sure in an accumulator is reaching 1650 psi (pre-
charged pressure), the hydraulic pressure will rapid-
ly drop to zero since the piston has reached it’s end
position and thereby seizing to create pressure into
the system.
2.5
Warning system
An amber caution light is provided on the Central
Warning Panel. The light will come on together with
the MASTER CAUTION light and single chime in
case of low pressure in main or emergency accu-
mulator or high fluid temperature in the main reser-
voir.
It shall be noted that low pressure in one or both
brake accumulators always results in low pressure
in the main accumulator. This means in practice
that low pressure in any of the four accumulators
will trigger the warning system.