Level-D 171 for ATPL Systems
Oneday_soon
Yes I used it as you indicated.
It was useful not only for the systems (A/C, power, gen, hydraulics) but also for the FMC, autopilot, EADI, EICAS etc etc.
in short - yes I am glad i spent the $ on it, made the diagrams and explanations in the books make much more sense.
Cheers,
RR.