This document presents a paper on aircraft hydraulic systems. It describes the basic components and operation of hydraulic systems used in aircraft, including hydraulic pumps, valves, actuators, and other components. It provides examples of typical hydraulic systems for Boeing and Airbus aircraft. It then discusses various parameters of aircraft hydraulic systems such as hydraulic fluid, pressure, temperature, and flow rate. Finally, it outlines the testing process for aircraft hydraulic systems.

1. A
PAPER PRESENTATION
ON
“AIRCRAFT HYDRAULIC SYSTEM”
Presented By
THORAT SANDIP
SHINDE GANESH
DEPATMENT OF MECHANICAL
ENGINEERING
AMRUTVAHINI COLLEGE OF ENGINEERING, AMRUTNAGAR,TAL –SANGAMNER, DIST–AHMEDNAGAR, (M.S)
INDIA-422608
UNIVERSITY OF PUNE
(2016-2017)

2. This presentation first describes the development and application of aircraft hydraulic
systems with emphasis on the basic structure of hydraulic systems, a typical hydraulic
system in the Boeing family of aircraft, and a typical hydraulic system in the Airbus
family of aircraft. Then, basic parameters of aircraft hydraulic systems, including
hydraulic fluid, hydraulic pressure, fluid temperature, fluid flow rate, hydraulic pipes,
and pressure pulsation, are provided. Afterward, the main components of aircraft
hydraulic systems are introduced, including aircraft hydraulic pumps (engine-driven
pump and AC motor-driven pump), power transfer units, priority valves, control
valves, check valves, hydraulic accumulators, hydraulic filters, hydraulic reservoirs,
fluid cooling systems, hydraulic actuators, and redundant hydraulic actuators. Finally,
the proof test of an aircraft hydraulic system is presented and discussed, with special
attention to the hydraulic system testing process.
Abstract
Presented by
Thorat Sandip
Shinde Ganesh

3. INTRODUCTION
 Hydraulics is based on the fact that liquids are incompressible
 Hydraulic system is a system where liquid under pressure is used to
transmit energy
 In it a hydraulic pump converts mechanical power to hydraulic power
 An actuating cylinder converts hydraulic power to mechanical power.

4. A SIMPLE HYDRAULIC SYSTEM

5. DEVICES USING HYDRAULIC
SYSTEMS IN AIRCRAFTS
 Gun turrets
 Auto pilot
 Shock absorption systems
 Dive, landing, speed and flap brakes
 Bomb bay doors
 Doors and hatchways
 Landing gears, wing flaps, etc…

6. PRINCIPLES OF OPERATION
 Governed by Pascal’s law
 The oil is in contact with both
sides of the piston head but at
different pressures. High
pressure oil may be pumped
into either side of the piston
head.
 The selector valve determines to
which side of the actuating
cylinder the high pressure oil
(red colored side) is sent.

7. PARTS OF THE POWER
SYSTEM
 RESERVOIR
 ACCUMULATOR
 FILTER
 POWER PUMP
 SYSTEM RELIEF VALVE
 PRESSURE REGULATOR

8. POWER SYSTEM

9. RESERVOIR
FUNCTIONS
 Holds reserve supply oil to account for normal
leakage, emergency supply of oil, volume changes,
thermal contraction of oil,
 Provides pressure head on the pump, a place to
remove air or foam from liquid, air space for
expansion of the oil due to temperature changes
etc

10. ACCUMULATORS
PRINCIPLE
 Gas valve lets in
compressed gas at ½
system pressure
 Diaphragm pops up &
oil is sent through
system
 When system
pressure>accumulator
pressure, diaphragm
deploys

11. ACCUMULATORS
USES
 Absorbs the shocks due to rapid pressure
variations in a hydraulic system
Helps maintain a constant pressure within the
hydraulic system
Helps the hydraulic pump under peak
pressure loads
It is an emergency source of power
Spherical shape is preferred for accumulators

12. POWER PUMPS
FUNCTION
 Is to change mechanical horsepower to
hydraulic horsepower
TYPES
 Gear pumps: move fluid based upon the
number of gear teeth and the volume
spacing between gear teeth.
 Piston pumps: move fluid by pushing it
through the motion of the pistons within
the pump

13. POWER PUMPS
PRINCIPLES OF GEAR
PUMPS
 The liquid from the
reservoir is pushed between
the gear teeth.
 The oil is moved around to
the other side by the action
of the drive gear itself and
sent through the pressure
line.

14. POWER PUMPS
PRINCIPLES OF
RECIPROCATING
PISTON PUMP
 As the cylinder block
rotates, space between
the block and the
pistons increase, letting
in more oil.
 As the block rotates
from bottom dead
center, the reverse
occurs and the pistons
push oil out through
the outlet

15. HAND PUMPS

16. Selector Valves
 Position (1) is the position of the selector valve, for example,
upon the extension of the landing gear or the lowering of flaps.
 Position (2) is the position of the selector valve upon
retraction of the landing gear or the raising of the flaps

17. FLOW EQUALISER
 If wing air loads on one wing are
greater than on other, during wing
sweep back or sweep forward,
motion occurs unevenly.
 To synchronize wing sweep back or
sweep forward flow equalizer used
 flow equalizer is made up of two
power pumps placed side by side in
which the drive gears of both
pumps are connected

18. ACTUATION CYLINDER
 The function is to take the pressure & hydraulic fluid flow &
change them into linear or rotary motion.
 Single piston double rod is an equal displacement cylinder used in
aileron system or automatic guidance system
 Double piston-double rod actuating cylinder used in bomb bay
doors

19. ADVANTAGES
 It is lighter in weight than alternate existing
systems.
 It is dead beat, that is, there is an absence of
sloppiness in its response to demands placed on the
system.
 It is reliable; either it works or doesn't.
 It can be easily maintained.
 It is not a shock hazard; it is not much of a fire
hazard.
 It can develop practically unlimited force or torque.

20. CONCLUSION
Hydraulic systems determine flight worthiness,
usability and reliability.

21. References
•http://aerospace.eaton.com/news.asp?articledate=06/01/03&NewsCo
•http://www.tpub.com/content/aviation/14018/css/14018_17
8.html
Air Force Research Laboratory
http://www.afrlhorizons.com/Briefs/0006/VA9902
www.hydraulic equipment.com

23. ANY
QUESTIONS?