|March 18, 2008||HOME|
The work day started off with my husband Bill receiving a call from Dennis Mangan. He and Dennis discussed an RV that crashed, the cause of which some folks speculated was the failure of the Van's electric boost pump to self prime when a tank is run completely dry.
To resolve the issue, Bill set up a test. We were perfectly positioned for that because the boost pump is installed, but has never had fuel in it. The airframe is on its side which allows 36 inches of draw -- far more than any RV installed pump would ever have to draw in order to self prime under the very worst of conditions.
Whatever may have come to mind, this is a large cup of auto gas.
The one quart container of auto gas was positioned 36 inches below the pump. The plumbing was complete through the pump and out through the gascolator on the firewall.
The end of the tubing had been pinch cut and had a restricted opening that would reduce the fuel flow. He left it that way to provide a more difficult condition for the pump.
The result: It took 4 seconds for the pump to draw a 36" head, self prime and deliver fuel through the gascolator. The pump clearly self primes with a lift capacity well in excess of what is needed to draw from an RV wing tank. Furthermore, the boost pump is nonrestrictive in all positions which means, it allows the mechanical pump to draw freely when it is turned off.
This doesn't tell us why the subject RV crashed, but it does clear up the speculation that the Van's boost pump doesn't self prime. It certainly does.
While all the testing was going on, I installed 2 main ground busses inside the firewall. There is one on each side for. Even though the 2 electrical system can are separate even with a common ground, I felt it would be good practice to install one ground buss for each electrical system. It also keeps it in mind that there are 2 systems.
The main ground stud for each ground buss is on the engine side of the firewall and will be grounded directly from its respective battery.
Jumping around as I like to do, I went back to work on the radio rack, finally drilling and fitting the trays in place.
This is the top of the stack as it will be riveted to the panel.
In order to make sure everything fit, I temporarily inserted the radios into their trays and checked the fit. That's the order of the radio stack.