Once again I need some help. My mechanic discovered a fuel leak at the root of the left wing of my B23. We are not sure of the best way to access this area to find the leak.
Bob Steward A&P IA:
Well, the ONLY way to access it, short of using a chain saw , is to take the access panels off the inside of the fuselage and peer into the area with a flashlight and a mirror. There are two access covers on each side under the carpet/upholstery, in the “kick panel” area below the door(s). There are so many screws on them that you’ll be certain you are getting carpal tunnel syndrome by the time you get them all off.
I’ve found the fuel line(s) loose buy just half a flat’s rotation, and this caused a noticeable blue/brown stain at the wing root. Hopefully you won’t have any other source of leaks, as its quite difficult to work in that area without removing the wing!
Bob Steward A&P IA
Good advice from Bob, as always. Note that the screws in the access panel are AN525 washer-head structural screws. Because of the door opening area, the access panel is a structural component that helps form a “box section” below the door. Many of these screws may be found stuck and rusty. Once you get them out, make sure you replace any bad ones with AN525 screws, and spray the clipnuts with something like LPS2 or LPS3 prior to reassembly. Don’t use the weaker stainless-steel truss-head screws here.
A common source of seepage leaks is the fuel level transmitter itself. They often seep fuel out of the center stud seal. Trying to stop it by snugging the bottom nut on the sender stud is pretty “iffy”; a better bet is to drain the tank, pull the sender, and send it to someplace like Air-Parts Of Lockhaven for overhaul. Phone: 1-800-443-3117; 1-570-748-0823;
Hopefully you’ll get lucky, as actual fuel tank leaks are fairly uncommon on these planes.