Basic hydraulic systems

1. Aircraft Hydraulic
Systems
Abdalrahim AbuDayya

2. Basic Hydraulic System
•A valve is
opened, the
hydraulic flows
into the actuator
and presses
against the piston,
causing it to move
and in turn move
the attached
control surface

3. General Uses

Used for flight control, actuation of flaps, slats,
weapons bays, landing gear, breaks

Provides the extra force required to move large control
surfaces in heavy aerodynamic loads.

4. General Specifications
 Several
different Fluids
 MIL-H-5606,
 General
MIL-H-83282, and MIL-H-81019
Temperature Ranges : -65°F to 295°F
 Pressures:
 Airbus
A380 has 5000psi hydraulic system
 Typical
commercial airline pressure is 3000 psi

5. Problems with Hydraulics

Heavy

High maintenance


Adds cost and creates a logistics problem
Requires space (pumps, hydraulic lines, etc.)

6. Possible Improvements

Electric Actuators

Consists of a small electric motor, pump and actuator ram requiring about 1
pint of hydraulic fluid

Flight tested by NASA’s Dryden Flight Research Center on a modified F-18.

Provides significant weight savings by eliminating pumps and hydraulic lines

Also could decrease required maintenance

7. Electro – Mechanical Actuator

8. Impact on Design

Need to allow sufficient space for required hydraulic
systems

Weight of the system must be accounted for