The document discusses the hydraulic system used in HAL Avro aircraft. It notes that hydraulic systems are used to operate components like landing gears, flaps, and brakes due to advantages like being lightweight, easy to install and inspect, and highly efficient. It then describes the key components of the hydraulic system, including the reservoir, accumulator, actuators, engine-driven pump, hand pump, and others. It provides details on how these components work together to build up and regulate hydraulic pressure for operating aircraft systems.

1. SUBMITTED BY-
TANUSH TRIPATHI(1309120103)
SUBMITTED TO-
Mrs. DIVYA CHANDRA

2.  AIRCRAFT HYDRAULIC SYSTEMS
 Hydraulic systems are not new to aviation .In earlier aircrafts hydraulic systems
are used in brake systems. As aircraft became more and more advanced, newer
systems with hydraulic power were developed.
 Today the operation of landing gears, flaps, flight control surfaces and brakes is
largely accomplished with hydraulic power systems.
 Hydraulic systems have many advantages as power sources for operating various
aircraft units
 Hydraulic systems are light weight
 Installation ,inspection of hydraulic systems is easy.
 Hydraulic systems are almost 100 percent efficient ,with only negligible loss due to
fluid friction.

3.  HS-748 aircraft was started from 1980 for Indian Air
Force.45 aircraft have been overhauled till March 96. In
addition to this, refurnishing, Cat-B and minor repairs of
HS-748 aircraft are also being carried out. As the aircraft
of IAF are in healthy condition, it has been decided to
upgrade the control system, Navigation System and Auto-
Pilot Units etc with latest technology for getting better
utilization of aircraft to the customer. In the same line
MOD-S Transponder also has been fitted to have better
communication.
 Max take off wt. :- 43500LBS
 Max landing off wt. :- 41500LBS
 Max zero fuel wt. :- 36300LBS
 Max crusing speed :- 245knots
 Crusing height :- 20000m

4.  HS-748 AVRO AIRCRAFT
 The HS 748 Hawker Siddeley is a medium sized turboprop airliner designed by
British firm Avro.
 The aircraft uses two Rolls Royce turboprop engines.
 This aircraft is also license produced in India by Hindustan Aeronautics Limited
(HAL-748).
 Hawker Siddeley also used the HS-748 for their HS 780 Andover- a transport
aircraft built for Royal Air Force.
 HAL built 89 Avro aircrafts in India ,72 for the Indian Air Force and 17 for Indian
Airlines Corporation.
 Production of HAL -748 ended in1988.
 HS 748 today are used as passenger aircrafts , fighter aircrafts, as well as for bulk
fuel hauler.

5.  Crew: Three (two pilots + one passenger attendant)
 Capacity: 40–58 passengers
 Payload: 5,136 kg
 Length: 20.42 m
 Wingspan: 31.23 m
 Height: 7.57 m
 Wing area: 77 m²
 Empty Weight: 12,327 kg
 Max. Takeoff weight: 21,092 kg
 Cruise speed: 452 km/h
 Range: 1,715 km (with max payload)
 Service ceiling: 7,620 m
 Wing Load: 274 kg/m²
 Power/mass: 0.161 kW/kg

7.  The HAL was founded on 23rd December 1940 as Hindustan Aircraft Pvt limited
at Bangalore by late Walchand Hirachaand in association with government of
Mysore for the aircraft making in India.
 The organization and the equipment's for the factory at Bangalore was set up by
Intercontinental Aircraft Corporation of New York.
 In august 1963 Aeronautics India Limited was incorporated as a company wholly
owned by the government of India to undertake the manufacturing of MIG-21
Aircraft under license.
 In 1st October 1964 ,the merging of Hindustan Aircraft Pvt Ltd and Aeronautics
India Limited led to formation of Hindustan Aeronautics Limited(HAL)

8.  The division was set up in 1960 to manufacture HS-748, but with passage of time
,the division now manufactures varieties of aircrafts , structural assemblies, paints,
and detailed part manufacturing of various components.
 Current Activities of TAD Kanpur:-
 Manufacturing of HAL Dornier 228 Aircraft
 Servicing and overhaul of AVRO Aircraft
 Servicing of engines of Unmanned aerial vehicle (UAV)
 There are 8 hangars in the factory
 Some of the other facilities at TAD Kanpur :-
 Machining Facilities
 Composites ,Plastics
 Sheet Metal, Welding
 Quality Control Facilities

11.  HAL is the largest defence PSU among 9 defence PSU’s in India today.
 HAL is the only company in the world which manufactures both frames as well as
engines of the aircraft.
 More than 3800 aircrafts and 4500 engines have been produced by HAL.
 HAL is a navratna company since 2007.
 HAL has 20 production and 10 R&D centers in India.

13.  The Hydraulic Power System comprises of a main system supplied by engine driven
pumps , and an auxiliary system provided with a hand pump.
 The auxiliary system supplies pressure for ground servicing and for use in emergency if
the main system fails.
 In an aircraft , the operation of Landing Gears ,Doors, Flaps , undercarriage, steering
,wiper and Brakes is largely accomplished with Hydraulic Systems .
 The Hydraulic systems in an aircraft are based on pascal’s law and Bernoulli's principle.
 Different components of hydraulic system in an aircraft are:-
 Reservoir
 Accumulator
 Actuators
 Filter
 Engine driven Pump(EDP)
 Hand Pump
 System Relief Valve
 Pressure Regulator
 Cut-out Valve

15. RESERVOIR
 The function of reservoir is to hold reserve supply oil to account for
normal leakage, emergency supply of oil, volume changes, thermal
contraction of oil,etc.
 Reservoir also provides pressure head on the pump.
 Reservoirs are usually made of aluminum.
ACCUMULATOR
 The function of accumulators is to absorb the shocks due to rapid
pressure variations in a hydraulic system.
 It also helps to maintain constant pressure within hydraulic system
ACTUATORS
 An actuator is a mechanical device that takes energy & converts it to
a desirable form for usage or application.
 In hydraulic systems the actuator converts Hydraylic energy into
mechanical systems

16.  The engine driven pump is the pump that provides the primary
hydraulic power in many aircrafts today such as Boeing ,Airbus
,Sukoi and other passenger aircrafts and fighter jets.
 The typical EDP configuration is a pressure-compensated, variable
displacement axial piston pump capable of varying the volume of fluid
delivered to maintain hydraulic system pressure.
 The Engine driven pump is connected directly to the turboprop engines.
 As the barrel rotates, the pistons reciprocate within their bores, taking
in and discharging fluid through a stationary valve
 The hanger is supported by bearings that permit angular rotation about
an axis perpendicular to the cylinder barrel centerline. By changing the
angle of the hanger, the length of the piston stroke varies, resulting in a
change in pump displacement.

18.  The hand pump was used as primary pump in older aircrafts.
 Nowadays the hand pump is used in aircrafts either as a emergency pump(if
primary pump fails , then this pump can be used) or for testing purposes.
 Several types of hand pumps are used: single action, double action,
and rotary , the double action pumps are mostly used since they are
highly efficient.

19.  The Hydraulic fluid , from reservoir goes into the engine driven pump.The
reservoir is connected to EDP through a high pressure relief valve.The maximum
pressure that can be sustained by relief valve is 3300 psi.
 The EDP is connected to a cut out valve which is connected to the Actuators of
aircraft system.
 When the aircraft is on the ground ,EDP is used and pressure is increased using
EDP.
 But when the aircraft is in flying mode, the EDP is disconnected from the aircraft
using a cutout valve.
 The cutout valve is further connected to tank using a venting valve.

21.  It is lighter in weight than alternate existing
systems.
 It is reliable .
 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.
 This is highly efficient systems because of
negligible friction losses.

23. SNAGS REMEDIES
1. Services fail to respond to
engine driven pump or hand
pump
Ensure sufficient oil in system. If
oil is sufficient then replace the cut
out valve
2. System fails to build up
pressure when powered by hand
pump
Hand pump should be checked for
its proper functioning.
3. Main accumulator gas pressure
is high
Check the accumulator gas
pressure .Release some gas and
reduce the pressure of
accumulator
4. Main accumulator gas pressure
is low
Release gas pressure and inflate
the accumulators to correct
pressure.
5. System pressure indicator gives
false reading
Relay and transmitter units may be
faulty and should be replaced.
6. Hammering noise from system Install a new cut out valve.

24.  Apart from hydraulic system of Avro aircraft as a part of our project, I have also
studied about Dornier -228 Aircraft ,the only difference between two systems is
that the Engine Driven Pump of Dornier aircrafts is equipped with a motor. The
EDP of Dornier aircrafts works all the time i.e when the aircraft is on the ground as
well as it is flying.
 Hydraulic systems ,in general are now used in most of the components of the
aircrafts. Due to its high efficiency and low frictional losses ,it has replaced most of
mechanical systems.
 Nowadays , hydraulic systems integrated with electrical systems are used
nowadays ,equipped with micro-processors and micro-controllers.