What was found
DURING A WALK AROUND, HEARD A POP, THEN NOTICED FLAMES WHERE THE EXTERNAL POWER CORD WAS PLUGGED INTO THE AIRCRAFT. THE AIRCRAFT WAS GROUNDED. MAINTENANCE REPLACED THE BACKUP POWER CONTROL UNIT IAW MM 24-41-05. AS A RESULT OF THE SPARKS, MAINTENANCE ALSO FOUND BURNT PINS AT SECONDARY EXTERNAL POWER RECEPTACLE. MAINTENANCE ALSO REPLACED SECONDARY EXTERNAL POWER RECEPTACLE PER AMM 24-41-04 (SEE AALA201901169019) AND ACCOMPLISHED TEST PER AMM 24-41-00, NO FAULTS NOTED. MAINTENANCE ALSO ACCOMPLISHED AN INSPECTION FOR THE ASSOCIATED WIRING PER SSM 24-41-11 AND 24-41-31 AND PERFORMED SATISFACTORY OPERATIONAL CHECK.