PTU(Power Transfer Unit) B737NG

[owl-attack]

Hello guys

An elementary question on the working of PTU

I Understand the conditions required for the PTU to operate:

Sys B EDP pressure drops below limit
Flaps less than 15 but not up
Airborne

and I also understand that is used to operate autoslats and LE flaps and slats

But I seem to be getting very confused here. What do they exactly mean when they say PTU is used to operate Auto-slats and LE flaps and slats. Why can't the Sys B EMDP be used to operate these ( only the Sys B EDP has failed , Sys B EMDP is still working fine)


2. When the FCOM says PTU is used to operate LE Flaps and slats " do they mean it is used to retract after take off and extend while landing?


Thanks guys !