Oct 13

PTU automatic operation

Good morning everyone, hope this question won't be the 1 million dollar one.

Ptu description says that for automatic operation we have to be airborne, sys b engine driven pump pressure drops below limits and in case of non short field performance flaps have to be less than 15 but not up.

So, let's imagine that we are on final and we have eng 2 failure with flaps 40.

All the conditions mentioned above are satisfied, but with the exception of the flaps, so how come we are able to retract the flaps to 15 (in case we need to, for performance considerations), if PTU is not working automatically?

Thank you


True, but I don't understand.

Why the system talks about flaps position?

What the EMDP of failed engine has to do with flaps extension?

So the PTU only works with flaps 15 or less, otherwise the EMDP does the work?



Flaps are driven by the B hydraulic system. if you still have the EDMP (you’ve only lost the EDP) you still have B system power and can run the flaps


PTU only operates leading edge and gives the additional volume of fluid to run slats and LE flaps at normal rate due to the EDP being lost. If you didn’t have the flaps out you wouldn’t need it to help


Thank you Ian, your simple explanation really helped me out :)