Warns Of Potential Maintenance Oversight For Installed Batteries

The FAA had published a Special Airworthiness Information Bulletin (SAIB) for Narco Emergency Locator Transmitters (ELTs), that there is a potential maintenance oversight related to inspection requirements. This maintenance oversight could lead to undetected battery leakage and subsequent corrosion that could result in the ELT becoming inoperable. Regulatory action is not required at this time since the airworthiness concern is not an unsafe condition that would warrant airworthiness directive action under 14 CFR part 39.

An FAA safety recommendation highlighted areas of concern with several inspection issues. One issue was that battery acid was corroding the ELT cover. The inspector found that the corrosion had rendered the ELT inoperable since the terminals connecting the ELT to the battery were no longer able to conduct electricity. ELT inspection requirements and battery replacement intervals are mandated in 14 CFR 91.207(c) and (d). If the inspection requirements and replacement intervals are followed, battery leakage should not occur. The inspector also noted that if ELT battery leakage was allowed to continue, combined with the potential for co-locating the ELT near flight control cables, it could lead to an unsafe condition.

Although there have been no unsafe conditions caused by leakage, which accompanies an advanced level of corrosion, we recommend that all owners, operators, and maintainers increase awareness of corrosion on ELT battery terminals. 14 CFR 91.207(d) outlines the inspection requirements on aircraft every 12 calendar months. If corrosion is discovered on the ELT or on the battery terminals, we recommend inspecting for damage on mountings and flight control cables in the area around the ELT, in addition to following any maintenance requirements to replace the battery and/or ELT with airworthy part(s).

FMI: SAIB