WR963’s pumps are electric. We have a setup to test them (off aircraft) electrically and that they pump fuel through.

Regards,

Rich

I wonder why they don’t fail on test? Do you pressurise them when testing

Richard

I need to catch up here.

In that image, there’s a banjo bolt to the left, and a thingy on the right. If there is no fuel fitting in the cover, one is the inlet and the other is the outlet. I don’t know which without knowing the pump rotation. In case it isn’t obvious, the pump pumps by carrying fuel around the outside of the gears in the empty teeth. The fuel can’t get back to the inlet because of the meshed teeth in the middle

Does the one on WR963 have an electric motor as well? If so, there should be tests that can be done off the aircraft

Richard

Hmm – curiouser and curiouser

I’ve just taken the lid off a pump – marked up as a fuel pump.

It has steel gears inside, not fibre ones.

Do we have a mismatch of components perhaps?

Bruce

My comment ONLY applies to an impeller pump. With a positive displacement pump, like a piston or gear pump, blocking the outlet will increase pressure and load. Are you looking at a gear pump, or talking about the gears in the gearbox?

Richard

Thinking about it though, if the pump overpressures, it wouldn’t take much to slow the impeller down and with the motor fighting away at the other end of things, the gearbox is going to let go.

I’m late into this, so apologies if there is an element of sucking eggs

If these are impeller pumps, then blocking off the outlet reduces the load on the pump, not increases it. Maximum load is at maximum fuel delivery – with it blocked off the fuel travels around in the impeller going nowhere

We tested experimental Concorde impeller pumps that way – always start with the delivery side closed to spare the test rig

Richard