06/26/2021

Back to work full time so the Sling build really slows down.

Finished the install of the 2 wing root fuel pumps. The plumbing is finished for the fuels systems and should add robust safety with pressure supplied form each tank to the selector then to the Rotax pumps.

I will put the wiring/switch work under electrical when that taks is completed.


06/15/2021

After replacing most (but not all) of the rubber hose fuel lines in the forward firewall I began to re-think the fuel delivery from the tank to the firewall. I have never been happy with the TAF fuel pump added just down stream of the Fuel Select Valve for the following reasons....

1) It is one pump (with a bypass) for both tanks. The reasoning is for the vapor pressure of the fuel. This is a valid reason as my airport is 6000' MSL and I routinely fly at 12, 000+ MSL. However, still not happy with just one pump.

2) The pump is located in the cabin. Multiple leaks points after the Selector Valve with the pump, bypass, and other connections

3) Noise and safety. Fuel pump instructions (on most pumps) ask that the pumps be installed near the fuel tanks and at the same level of the tank. While many pumps have a stated "Lift" height and should suction from the tank the best application in nearest the tank. I did a test on the suction Lift of the pump and was not impressed. For these reasons I would prefer the pump to be in the wing roots.

I decided to purchase 2 Facet electronic pumps that will reside in the wing roots. The power to the pumps will be supplied to each individual pump at any one time via an SPDT NC-NO micro switch. This switch will be located on the bottom side of the selector plate just in front of the valve assembly and the fuel selector arm will activate the respective pump with the selector lever position. All power for these pumps will come from the A or B pumps switches on the main panel.

Anytime the A or B Rotax pumps are selected, power will be supplied to either wing root pump based upon the fuel selector position.

First, I removed the installed TAF pump and bypass. The supply line then was connected directly to the firewall ( as in older designs!). I then had to decide how to mount the pumps in the wing root. Using the existing rib required additional support and stiffening. I fabricated additional support plate and shaped it with a metal brake to add stiffness. These will be riveted to the rib.