Term paper

on discipline " Aircraft systems "

Theme: Hydraulic system of Boeing 767

Performed by:

Name: Suprunets M.V.

Group: FLA 505

Examined by S.Yutskevych

Kyiv 2015

General

Airbus A320

The aircraft is equipment with three continuously operating hydraulic systems called Blue, Green and Yellow (Figure 1). Each system as its own hydraulic reservoir as a source of hydraulic fluid. Normal system operational pressure is 3000 PSI(2500 when powered by the RAT). Hydraulic fluid cannot be transferred from one system to another.

The Green system (System 1) is pressurised by an Engine Driven Pump (EDP) locaed on No. 1 engine which may deliver 37 gallon per minute or 140 L/min

The Blue system (System 2) is pressurised by an electric motor-driven pump capable of delivering 6.1 gpm or 23 L/min/ A Ram Air Turbine (RAT) can provide up to 20.6 gpm or 78 L/min at 2175 psi in emergency condition.

The Yellow system (System 3) is pressurised by an driven by No.2 Engine. An electric motor driven pump is provided which is capable of delivering 6.1 gpm or 23 L/min for ground servicing operation. This system also has a hand pump to pressurise the system for cargo door operation when the aircraft is on the ground with electrical power unavailable.

Each channel has the provision for the supply of ground-based hydraulic pressure during maintenance operation. Each main system has a hydraulic accumulator to maintain system pressure in the event of transients. See Figure 2

Each system includes a leak measurement valve (shown as L in a square on the diagram), and a priority valve (shown as P in a square). The leak measurement valve is positioned upstream of the primary flight controls and is used for the measurement of leakage in each flight control system circuit. They are operated from the ground maintenance panel. In the event of a low hydraulic pressure, the priority valve maintains pressure supply to essential systems by cutting of the supply to heavy load users.

The bi-directional Power Transfer Unit (PTU) enable the Green or the Yellow systems to power each other without the transfer of fluid. In flight in the event that only one engine is running, the PTU will automatically operate when the differential pressure between the systems is greater than 500 psi. On the ground, while operating

Figure 1 Hydraulic system of A320

the yellow system using the electric motor driven pump, the PTU will also

allow the Green system to be pressurised.

The RAT extends automatically in flight in the event of failure of both engines and the APU. In the event of an engine fire, a fire valve in the suction line between the EDP and the appropriate hydraulic reservoir made be closed, isolating the supply of hydraulic fluid to the engine.

Pressure and status readings are taken at various points around the systems which allows the composition of a hydraulic system display to be shown on the electronic Crew Alerting and Monitoring (ECAM)

Fures 3 and 4 shows a hydraulic system

control panel and system display during normal operation of the hydraulic system. Normal system operational pressure is 3000 PSI.

Figure 3 - Control panel

Figure 4 – System display