No need to wait until engine one spool down at the gate before switching off the Y ELec pump. PTU is inhibited with parking brake set.

Indeed. Most Captains take the PB off after the chock signal, though. Hence, the commonplace "what's that noise?"

if both engines master OFF (or both ON, but not the case), PTU Auto and diff press >500 psi, it will run independently of the park brake.

Runs every time I come onto stand after doing single engine taxi once engine one shut down and the parking brake is set.

PTU will run during engine 1 shutdown , and not when parking brake is set with Y ELEC pump OFF .

Citation2
Any reference for parking brake and PTU connection? Because during ENG1 start it comes on as a test.

Right, cause both engine master OFF (as long as diff HYD press > 500 psi)

Right again, because 1 engine master ON, the other OFF and Park brake ON and Nose wheel steering not in towing position :)

Yes, because both engines master ON (as long as diff HYD press > 500 psi and PTU sw in auto)

FCOM DSC-29-10-20 PTU (logic)

:ok:

Gryphon
Thanks.

And a cant understand what are the difficulties in PTU running for several seconds? Is it so important to avoid it?