Refueling Part 2

Arhur asked,

Helmis, This happen in Pucallpa, Peru, during a Boeing 737-200 refueling, as you explain, the aircraft system controls the max. level in the tanks, but there must be a pressure sensor as a safety device (pressure set a little more than 50 psi???) that delivers flow over the wing, when the tank is full…..is that right?? If the refueler delivers fuel at 50 psi, the aircraft system must stop the flow when it sense an excessive pressure in the line or when the tanks are full….the option to deliver excess flow overwing is a risk condition...probably on these old airplanes...or the new generation units have other system to avoid fuel spills in this cases?? Thank you, for your answer.

Flighteng replied,

Aircraft system only control the quantity, there is no control for pressure as far as aircraft system is concern. Take a loook at the refueling panel, there is a warning of maximum pressure allowed during refueling which is 55 psi, this have to be taken care by engineers who doing the refueling plus the bowser operator as well.

From 737-200 to classic and NG, the refueling system is almost the same, only improved instrumentation plus in NG you can set how much fuel in KG or LBs which it will automactically stop when it reach that level.