Rusty T,
There is an AD out that is crippling most aircraft with aftermarket STC'd fuel tanks. I believe it covers all CRJ's MD-80 series, most 737 series and 727's , airbuses, Boeings and Fokkers. Basically, anything with an added on fuel tank. They either have to disconnect the fuel tank or provide some sort of inert gas system ( as the US Air Force uses) to prevent sparks or arcing from explosions. This has caused a crisis for the new CRJ programs as well as the MD-87 aircraft and 737.
Maybe someone with more knowledge on the matter can chime in...