Transport Canada CF-2020-07

Requires inspections and replacements of the emergency light battery (ELB) pack if internal batteries are four years are older. AD also includes a new restoration task to minimize risk of fire. This action stems from a report of smoke and signs of an overheating from the ELB on an in-service airplane. Follow-up investigation found excessive corrosion surrounding the internal lead acid batteries, which caused an electrical short circuit that led to the observed smoke and overheating. The reported event occurred in 2018 and the affected batteries were manufactured in 2004. The ELB manufacturer recommends a preventative replacement of the internal ELB batteries every 48 months.