I love the headerless tank in our plane when it comes to working on the panel -- Oh, you thought you were done with that area? Hmmm. Seriously though, one consequence was a problem with the boost pump. Our plane was built with a Dukes boost pump about ½ way up the firewall. It has written on it a big warning – “Never run dry.” I’ve come to the conclusion they mean it! It has failed twice in less than 135 hours, the second time with a leaking seal on the shaft so fuel would dribble out the vent. The first failure was prior to our ownership, so I can’t comment on the mode. I assume the problem happened because the wing tanks are below the pump mounting position, so if the fuel valve is left on, the lines would drain back to the tank level, emptying the pump. So every engine start was dry until the pump re-primed. I decided to re-plumb the pump and fuel valve. I changed the fuel selector valve to a used Cessna wing tip tank valve that is much easier to operate, plus much less flow resistance. That was mounted close (about ½ inch above for clearance of the fuel and hydraulic lines underneath) to the floor midway in the center console. Then I built an universal joint extension shaft that comes to the new fuel selector knob just right and below the indicator for the pitch trim wheel. The Dukes boost pump was re-mounted on the floor underneath the passenger seat. Now both pump and valve are below fuel level and stay flooded.

Only time will tell, but a point from a discussion with Dukes was that in Cessna (where they’re used extensively) service, the pumps run forever and only get serviced because of the 10 year rebuild requirement on the pump. So I have to believe it is *very important* to keep the Dukes type vane pumps flooded if you go headerless and take the mounting into account.

Charles R. Patton
LNC2 360JM