212man, is this not only true for a failure similar to the vespel spline problem where the pump windmills. If the pump seizes I thought the pressure drop was much less?? This I was told was the only failure mode Sikorsky had considered at the design stage and hence no check valves
No - not with the -104 mod that DCVC refers to. The check valve is removed under the ASB, to reduce the rate at which the non-scavenged module accumulates oil.
Only if the failed pump is allowed to windmill of course, if it is jammed for some reason then expect around 17 psi (as per the -103 set up)