One of the more interesting components of the MiG-23 is the PGL-30M Hydraulic Powered Speed Regulator, a device that uses fuel to feed a vaned drive which in turn powers the AC generator.
Rather than using a complicated gear reduction mechanism to drive the AC generator from the engine rotation, the designers at MiG decided to use fuel pressure through a fluid labyrinth to obtain the constant RPM needed by the AC generator.
This works beautifully, producing a constant (plus or minus 2%) RPM... except when the PGL-30M leaks. Of course, when it leaks, it leaks fuel, which is the case with the Cold War Air Museum's MiG-23.
The MiG-23 doesn't do anything in a small way when it comes to fuel. Until the device was removed it was necessary to put a 150 gallon plastic stock tank under the aircraft to catch the drip.
The museum has located a replacement regulator, which we expect to be arriving in the near future.