Originally Posted by
IFixPlanes
Already mentioned
here.
Use the one from the EMDP.
I believe you only mentioned about a case drain for the EDP(engine driven pump) as quoted....."
OK, more details.
If you look closer on the EDP, you see 3 hydraulic lines connected to the pump.
The supply line from the reservoir, the pressure line to the system and ... the case drain. There is a small flow through the pump housing for lubrication and cooling purpose. These case drain flows even when there is no system demand/flow. But the case drain goes not go back directly to the tank. It is routed via 2 heat exchanger (case drain to fuel) in the wing tanks.
Without fuel in the tanks the complete system is getting to hot. "
I am pointing out that the electric pumps have the same thing(case drain). And why would I use the B pump overheat(EMDP as you call it) to tell if I have an overheat for the A Pump fluid.