The PTU is a reversible motor-pump located between the Green and Yellow hydraulic systems. It enables the green system to pressurize the yellow system, and vice versa, without fluid transfer. The PTU is automatically activated when the differential pump pressure output between the green and yellow systems exceeds a predetermined value (500 PSI). On the ground, when the engines are not running, the PTU enables the yellow system electric pump to pressurize the green system. Operation of the PTU is displayed on the ECAM page and also indicated via an ECAM memo.
PTU operation is inhibited when the:
PTU operation is inhibited when the:
- <Nosewheel steering in the towing position
- First engine is being started (PTU operation is automatically tested during second engine start)
- Cargo doors are operated and for 40 seconds after the end of cargo door operation
- Parking brake is ON and only one ENG MASTER switch is ON
- PTU pb is OFF
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