User manual

Part B Section 12.29
10 HYDRAULIC PRESSURE GAUGES
Three hydraulic pressure gauges are fitted
One gauge on the right hand side of the instrument panel indicates actual pressure in the
hydraulic system. This pressure bleeds away when the aircraft is not in use and can read
zero after a period of time.
The upper of the two gauges in the Nose reads the pressure in the 5-inch accumulator.
When the hydraulic system is completely discharged of hydraulic pressure it will indicate
the air pressure remaining in the 5-inch accumulator, normally 600 psi. When the hydraulic
system has a
Pressure greater than the air pressure in the 5-inch accumulator this gauge will then
indicate the higher pressure, i.e. the same as the pressure shown by the gauge on the
instrument panel.
The lower of the two pressure gauges in the Nose reads Emergency Brake Pressure, i.e.
the pressure in the 10-inch accumulator. The pressure in this accumulator is isolated from
the main hydraulic system by a non-return valve so that it is able to charge but not
discharge into the system. When the hydraulic system is completely discharged of
Pressure, this gauge will read the air pressure in the accumulator which should be 600 psi.
This pressure is the minimum required to achieve a full brake application. The pressure
should normally be 800-1000 psi.
Taxiing should not commence if the Brake Accumulator Pressure is below 800 psi.
Normal operating pressure for the hydraulic system is 800 -1000 psi, and with all systems
operating this is the pressure which should register on all three gauges.
Stichting Catalina PH-PBY Rev No: 00
18 May, 2004 Page: 3