Fuel Vent System

One system that is very important is the venting system of the wings and fuselage fuel tanks. As fuel is used during engine running or during refuelling a tank, naturally the empty space has to be filled or purged with air. Hence the fuel venting system. Without this system a fuel tank could in a worse case scenario implode.

I noticed that the fuselage vent gauge was stuck and removed the transmitter which supplies the gauge with its reading, I also removed the gauge to assess and  'match' the two units after bench testing. I found the internal moving coil to be stuck in the transmitter and as there are no spares available I had no choice but to free it off with lubrication.  I then ran the gauge up and down full scale in order to to test the system out.

Normal operating pressure is 2.5psi - 4.5 psi. The system is 'red lined' at 5 psi for safety purposes and 8 psi is the absolute maximum pressure. The most we achieve at ground level is around 2.5psi.

Pictured, the gauge, transmitter and a spare cockpit vent panel

It was all re-fitted back in today and showing the correct reading with electrical power on and fuel pressure without engines running.