What was found
EXTERNAL POWER ANNUNCIATOR WOULD NOT EXTINGUISH. FOUND AFT STIFFENER IN LT NACELLE AFT SKIN, HAD CHAFED THRU INSULATION ON ELECTRICAL LEADS THAT GO FROM THE EXTERNAL POWER RECEPTACLE IN THE WHEEL WELL, TO THE EXTERNAL POWER RELAY IN THE LT NACELLE. THIS CAUSED THESE LARGE (6 OR 8 GAUGE) WIRES TO BE GROUNDED TO THE AIRFRAME. REROUTING OR BETTER ANTI-CHAFE PROTECTION. POTENTIAL FOR FIRE OR SEVERE ELECTRICAL PROBLEMS.