PTU ( Power Transfer Unit) | Airbus A320 PTU Functions

Airbus a320 ptu image download

Power Transfer Unit (PTU)

The  PTU is a type of hydraulic pump which is able to  transfer  power  but  not the system fluid.  It  transfers hydraulic power  between  two different systems.  Different  types of PTUs are used by different aircraft manufacturer depending upon their designs and requirements. Some PTU (Power Transfer Unit) can only transfer power in one direction while others can transfer power in both directions. PTUs can have a fixed displacement or variable displacement hydraulic pump types. Within the PTUs, there are essentially two units: a hydraulic pump and a hydraulic motor, which are coupled by a single drive shaft to allow power to be transmitted between the two systems. Each unit functions as a motor or a pump depending on the direction of power transfer.

Airbus A320 Series PTU

The PTU (Power Transfer Unit) is a reversible hydraulic motor pump located between the green and yellow hydraulic systems in aircraft. PTU enables the Green hydraulic system to pressurize the Yellow hydraulic system and vice versa. When the pressure differential between the Green and Yellow hydraulic systems is more than the 500 PSI, the PTU is automatically activated. When the aeroplane is on the ground and the engines are turned off, the PTU allows the Yellow hydraulic system to pressurise the Green hydraulic system through the Yellow Electric pump. The hydraulic page of the ECAM (Electronic Centralized Aircraft Monitor) displays PTU operation.

The PTU is inhibited

The PTU is inhibited in the following circumstance:

When only one ENG MASTER switch is on and the PARK BRK is on

When only one ENG MASTER switch is on and the nose wheel steering disconnect pin is inserted

When the PTU is turned off


When the cargo doors are opened and closed (inhibition of PTU continues for approximately 40 seconds after cargo door operation)

Airbus A320 PTU Logics

Airbus a320 ptu logic
Airbus A320 PTU Logic

Airbus a320 ptu push button
Airbus a320 PTU Push Button

PTU PB SW Functions

The following are the functions of the PTU PB Switch:

AUTO Postion:

Both the yellow and green electrohydraulic valves are open, and the bidirectional power transfer unit is armed.

When the pressure differential between the green and yellow systems is more than the 500 PSI, the power transfer unit activates automatically.

Note : On the first engine start, the Power Transfer Unit (PTU) is inhibited, and it is also tested automatically during the second engine start.

OFF Postion:

Both the Green and the Yellow System PTU Electrohydraulic valves close. 

Power transfer stops.

Airbus a320 hydraulic ecam page
Airbus a320 Hydraulic ECAM Page

FAULT Light :

This amber fault light comes on, and a caution appears on the ECAM Page.

If: Any of the following occurred

The green or the yellow hydraulic reservoir overheats

The green or the yellow hydraulic reservoir has a low fluid level.

The green or the yellow hydraulic system reservoir has low air pressure

The Caution light goes out when the crew selects OFF the Push button, except during an overheat. (The Caution light stays on as long as the overheat lasts).

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