Home-made refuelling rig

After I had my refuelling accident with the Savannah last summer which led to my having to replace its windscreen, I vowed that I’d find a way to top-up the wing tanks without having the risk that such a disaster might ever happen again.

The problem is due to the need to raise the fuel up to wing height which can be no mean feat if you want to do it in one go, as then the jerrican that you’re lifting can weigh as much as 20 kgs. And even when you’ve got it up there, you then have to find somewhere on the wing surface to stand it without causing damage to the wing skin. And even then you have to find a way of getting the fuel out of the jerrican and into the tanks without spilling any.

That was when my problem arose as I was using a hand-held, battery powered pump to do the job, which it did successfully until its outlet tube came off, flooding the wing with fuel before I had a chance to switch it off.

For me, any meaningful solution involves electric pumping. I know that there are some good manual fuel pumps available but they still leave you with the problem of somehow tracking the fuel level in the tank that you’re filling if you’re working at ground level, or taking the fuel container up onto the wing with you, with the attendant risk of accident once again.

I wanted to come up with a solution that didn’t involve raising the heavy container and still allowed me to check the level of fuel in the tank while I was pumping and to do that I needed to have remote access to the pump stop/start and also a pump that delivered fuel at a reasonable rate.

The latter requirement was satisfied by an American pump designed for high powered road and racing cars that delivers fuel at the rate of 10 litres per minute at a cost of only around $60. That seems to me to be both realistic and economic as it would allow an average top-up to be done in something like 2 minutes per tank. It was then a matter of working out some sort of set-up incorporating it.

I mulled over the basic design for a while and as I need something to hold a jerrican weighing about 20 kg with its contents, it couldn’t be anything too lightweight and flimsy. Plus as far as possible I wanted to use materials that I already had to hand and that could be worked using standard tools.

My design incorporates a backboard that supports the jerrican and is tilted backwards so the fuel runs towards a low point. The jerrican also needs to be held on an angle by a fairly robust frame so the low point is a corner below the filler outlet making it possible to almost empty it with the pump using an inlet tube that reaches down into the corner.

I have made the backboard from a piece of old contiboard type material left over from an Ikea kitchen fit that I did for a friend and I’ve used copper tubing for the jerrican support frame and legs – 12 mm for the jerrican support frame and 14 mm for the rig’s legs.

Here’s where the job is as of today. First, the front view of the basic backboard.

null

The rear view of the backboard

null

The front view with a jerrican in place.

null

Another view with the jerrican in place.

null

Top of the backboard with the pump and other items in place showing the general scheme of things.

null

The idea is that the in-line filter (top left), which is incorporated to ensure that only clean fuel reaches the aircraft tanks, will be securely mounted probably on the rear of the backboard. It will have 2-3 metres of tubing attached to it to reach up to wing level and there will be a plastic clothes peg arrangement on the end of the tube so the end can enter the wing tank filler mouth and be clipped securely to the lip that projects upwards leaving hands free.

The primer bulb will be used to prime the pump so it never has to run dry as it is spec’d at a high output and after being primed initially would always run wet in a vehicle. It will be attached to a length of stainless steel tubing that enters into the mouth of the jerrican and reaches down to its lower rear corner.

There will be an electrical junction box mounted on the rear of the backboard in which there will be connections for the pump, a push/release start/stop button on a flying lead about 2-3 metres long and flying leads about 10-15m in length that will connect via crocodile clips to my car battery with an in-line safety fuse.

The idea will be to climb up to the wing tank filler on steps and place the end of the fuel filler tube into position, taking the stop/start button with you. The rig will be connected to my car battery standing several metres away which will be a good safety feature.

In theory the rig could be connected to the aircraft’s battery either directly or via the cigarette lighter socket. However, I don’t want to do that (a) because there seems little point in discharging the aircraft’s battery when the car battery will be close to hand and (b) it will require having the aircraft master switch turned on which, in the case of the Savannah (bad design), starts to clock up engine time on the hour meter.

The pump is rated at 10 litres per minute so if it performs to spec, I’ll have a rig capable of doing an average top-up in about 2 minutes per side as I wanted. And even if this stretches to 3 minutes or so, I won’t mind too much.

The whole project should be finished and working ready for testing tomorrow and I’m rather looking forward to it.