Originally Posted by
Sloppy Link
“I've never flown the type, but it seems to me that there is never a time when both transfer pumps would intentionally be off together”
Yep, when main is empty and fuel is only being drawn from the supply tanks. In simple terms, when there is no fuel to be transferred from main to the supply tanks, the transfer pumps are turned off.
except that the transfer pumps don’t need to be turned off, unless they are the crappy ones. Why not get rid of the crappy ones and then things would be much simpler and safer? No-one has bothered to do a risk assessment of the downside of the crappy ones vs ensuring that the pumps are the Test Fuchs type. What price making the system more error tolerant?