SPECIAL AIRWORTHINESS
INFORMATION BULLETIN

SUBJ: Emergency Locator Beacon

SAIB:

NE-14-10

Date:

February 24, 2014

This is information only. Recommendations aren’t mandatory.

Introduction

This Special Airworthiness Information Bulletin alerts you, owners, operators, and maintainers of
Merl, Inc. Batteries, used in Narco Emergency Locator Transmitters (ELTs), that there is a potential
maintenance oversight related to inspection requirements in § 91.207 of Title 14 of the Code of
Federal Regulations (14 CFR 91.207). 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.

Background

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.

Recommendations

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).

For Further Information Contact

Caspar Wang, Aerospace Engineer, FAA, Boston Aircraft Certification Office, 12 New England
Executive Park, Burlington, MA 01803; phone: 781-238-7799; fax: 781-238-7170; email:
caspar.wang@faa.gov.