What was found
AFT EMERGENCY LIGHT WILL NOT ILLUMINATE USING THE EMERGENCY LIGHTS BATTERY. THEY DO WORK WITH MAIN DC POWER. // SIGNOFF// VERIFIED AFT EXIT SIGNS AT DIVIDER AND OVER LAVATORY DO NOT ILLUMINATE ON EMERGENCY POWER ALONE, ALSO NOTED EXTERIOR OVER-WING LIGHTS DO NOT ILLUMINATE EITHER. REMOVED AFT EMERGENCY BATTERY PN: 9913-1, SN:1558 IAW CESSNA560XL AMM CH: 33-50-01. TESTED BATTERY ON .BENCH REFERENCING CESSNA 560XL WDM CH:33-50-0 L FIGURE 03. WHEN MONITORING OUTPUT PINS 1, 2, & 4 AND SIMULATING LOSS OF POWER, FOUND THAT VOLTAGE WOULD DROP FROM ~9VDC TO ~5VDC IN UNDER 30SECONDS WITH NO LOAD DETERMINED BATTERY TO BE FAULTY. INSTALLED CUSTOMER SUPPLIED REFURBISHED EMERGENCY BATTERY PN:9913-1, SN: 2777 IAW CESSNA 560XL AMM CH: 33-50-01, AND ALLOWED BATTERY TO CHARGE ON GROUND POWER. OPS CHECK: GOOD REFERENCE FAA FORM8130-3, FORM TRACKING NO. 8TDFAOOO'I001001, WORK ORDER8TDFA DURING INSPECTION NOTED AFT R/H SEAT READING LIGHT DID NOT ILLUMINATE WITH SWITCH. FOUND CORROSION ON BULB MOUNTING SOCKET. REMOVED SOCKET ASSEMBLY AND VERIFIED BULB WAS GOOD ON THE BENCH, AND THAT THERE WAS A LACK OF CONTINUITY FROM TH~ CONNECTOR TO THE SOCKET. REMOVED CORROSION, VERIFIED CONTINUITY AND REINSTALLED LIGHT ASSEMBLY AND CONFIRMED PROPER OPERATION FROM SWITCH PANEL. WORK PERFORMED IA W CESSNA560XL AMM CH:33-20-02