What was found
WHILE CONDUCTING 91.207D, ELT SYSTEM INSPECTION NOTICED WET SPOT AT CORNER OF BATTERY PACK CARDBOARD. PACK HAD 1-2 MONTHS REMAINING ON LIFE LIMIT AND ELT WORKED PERFECTLY FURTHER INSPECTION REVEALED. 1 CELL IN BATTERY PACK LEAKY AND CORRODED. BATTERY VOLTS OK. NEW BATTERY PACK WAS INSTALLED AND ELT CHECKED IAW 91.207-OK. SUGGEST GOOD VISUAL INPUT AT YEARLY ELT SYSTEM CHECKS. (PTRS-EA212003B1136)