T-6B fuel system question


Well-Known Member
Supporting Member
Feb 24, 2008
Kanab, UT
I was looking over this document which describes the T-6B fuel system. Attached image is from slide 3.

The system uses two ejector pumps in each wing tank, one each for the fore and aft pickups These ejector pumps feed to a header, which uses a series (EDIT: parallel, not series) combination of an ejector pump and an (automated) electric boost pump to feed in to the engine pumps; high pressure fuel return goes to the header. All approximately conventional for a header-tank system from my understanding.

But while the diagram shows interconnected vent lines on the wing tanks, it doesn't show any venting on the header. Is this just an oversight in the diagram? My understanding is that maneuvering to very high or low pitch is likely to unport one of the wing tank ejector pump inlets, and I believe that in this case the pump will happily pump air to the header tank, yes? This is fine for transient operation since the header tank basically acts as a fuel/air separator... but that only makes sense if there's a way for the air to escape from the header tank.

Q1) In the specific case of the T-6B, what am I missing?
Q2) In the more general design case, is the basic approach here to just T in the header vent with the main tank vents?

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