What was found
LHR - FLT 121 - ELEC ARC REPORTED ABOVE SEAT 28HJ ALL READING LIGHTS IN AREA INOPERATIVE. APPROXIMATELY 30 MIN INTO FLIGHT, CABIN ATTENDANT AND PASSENGER REPORTED AN ELECTRICAL ARC/SPARK ORIGINATING FROM PSU/OVERHEAD BIN AT SEAT 28HJ. ALL READING LIGHTS ON RT CABIN INOPERATIVE. TEN MINUTES LATER THE REMAINING COACH CABIN READING LIGHTS BECAME INOPERATIVE. CARRIED OUT T/S AND FOUND PSS WIRING CHAFED AT OVERHEAD DECODER AT SEATS 28HJ DUE INCORRECT ROUTING OF WIRES ACCOMPLISHED AIRWORTHY REPAIR TO PSS WIRING AND CARRIED OUT ALL CHECKS OK. (M)