Line Check/AAR Ready light

[jaylw314]

I was surprised to find out this is modelled.

 

Various checklists and publications for AA refueling in the A-10C indicate you are supposed to press the Line Check button a few minutes prior to AAR.  This pressurizes the closed refueling port over the next few seconds.  Once it reaches a certain pressure, the AAR Ready light comes on and should stay on for a minute or two.  This acts as a leak check--if there is a leak big enough, the light won't come on, or will turn off quickly.  The manual suggests the Line Check button has no function, but it does indeed work this way.

 

After refueling and closing the refueling port, the port is pressurized again automatically to push fuel in the refueling lines into the fuel tank.  During this time, the Ready light will again turn on for a minute or two, which also acts as an indication the port has closed correctly.  

 

Both of the above are actually modelled, and if you've ever wondered why your AAR Ready light was on despite the port being closed, now you know!  What an amazing module!