A320 PTU Inhibition - FCOM
 

Hey everyone! It has come to my attention recently during One Engine Taxi procedures how the PTU seems to be inhibited after the ENG 1 start, but then starts running before the Y ELEC PUMP is turned ON.
I remember reading older FCOMs from years ago, and seeing a few "PTU Running conditions" eg. Park BRK not ON, etc....
Somehow, it appears these diagrams have now disappeared from newer FCOMs (MSNs 7500-10500) yet the same conditions pro PTU operations have remained.
Does anyone really know why this information could have been removed from the manuals? And more importantly, does the PTU still run under the same conditions as it did before?
This is ALL I could find on my FCOM. Can't`upload pictures yet so had to copy the text!

• ( 4) PTU pb sw
• AUTO: The bidirectional power transfer unit is armed and both the yellow and the green
• electrohydraulic valves are open.
• The power transfer unit runs automatically when the differential pressure
• between the green and yellow systems is more than 500 PSI.
• Note:The PTU is inhibited during the first engine start and automatically
• tested during the second engine start.
• OFF: Both the green and the yellow PTU electrohydraulic valves close. Power transfer
• stops.

• Ident.: DSC-29-10-20-00001 137.0001001 / 04 DEC 18
• Applicable to: ALL
• A bidirectional power transfer unit enables the yellow system to pressurize the green system and vice
• versa.
• The power transfer unit comes into action automatically when the differential pressure between the
• green and the yellow systems is greater than 500 PSI.
• The PTU therefore allows the griten system to be pressurized on the ground when the engines are
• stopped.

Thanks in advance! I'm really looking forward to learning more of the A320, since I've only flied it for a few months now.

I dont know why Airbus removed the PTU diagram you mentioned however the information can be found in the Landing Gear chapter in the tables that show interaction between landing gear and other systems.

i.e PTU will run ( if more the 500 PSI pressure diff)
1. Both engine masters off, or
2. Both engine masters on, or
3. Nose wheel not in the towing position and park brake off.

The above applies to “on ground”.