Ensuring the continued airworthiness of your single-engine piston aircraft is paramount for safety, and few components are as critical in an emergency as the Emergency Locator Transmitter (ELT). The Federal Aviation Administration (FAA) has specific regulations governing ELT battery replacement and testing, designed to ensure these vital devices are ready when needed most.1 Understanding and adhering to these rules isn’t just about compliance; it’s about safeguarding lives.
THE CRITICAL ROLE OF YOUR ELT
The ELT serves as your aircraft’s distress beacon, designed to automatically activate upon impact and transmit a signal on emergency frequencies.2 Modern ELTs primarily transmit on 406 MHz, with a low-power 121.5 MHz homing signal to aid search and rescue teams in the final phase of locating a downed aircraft.3 While older 121.5 MHz ELTs are still legal in the U.S., the Cospas-Sarsat satellite system, which monitors distress signals globally, ceased monitoring 121.5 MHz in 2009.4 This means that 406 MHz ELTs, which also transmit a unique digital code registered to the aircraft owner, offer significantly faster and more precise search and rescue responses.5
FAA REQUIREMENTS FOR ELT BATTERY REPLACEMENT
The FAA’s regulations for ELT battery replacement are outlined in Title 14 of the Code of Federal Regulations (14 CFR) Part 91, Section 91.207(c). For single-engine piston aircraft, these rules stipulate two conditions under which ELT batteries must be replaced (or recharged, if rechargeable):
1. CUMULATIVE USE: If the ELT has been in use for more than one cumulative hour. This includes actual emergency transmissions, as well as any extended testing that might deplete the battery. It’s crucial to be mindful of this, as even brief, repeated tests can add up.
2. EXPIRATION DATE: When 50 percent of the battery’s useful life has expired, as established by the ELT manufacturer under its approval. This is typically indicated by an expiration date legibly marked on the outside of the ELT unit itself. It’s not uncommon for these batteries to have a useful life of several years, but proper tracking of this date is essential.
Upon battery replacement or recharging, the new expiration date must be clearly marked on the outside of the ELT and meticulously entered into the aircraft’s maintenance records.6 This ensures a clear historical record and provides the next mechanic or owner with the necessary information for future maintenance.
It’s important to note that while some individuals may consider replacing individual cells within an ELT battery pack to save costs, doing so typically invalidates the ELT’s Technical Standard Order (TSO) certification. TSO’d equipment must be maintained in accordance with the manufacturer’s data, which almost always requires replacement of the entire battery pack with an FAA-approved part. This is a critical safety consideration, as an uncertified battery could compromise the ELT’s performance in an emergency.
FAA REQUIREMENTS FOR ELT TESTING AND INSPECTION
Beyond battery replacement, 14 CFR 91.207(d) also mandates regular inspections of the ELT system to ensure its continued airworthiness.7 For single-engine piston aircraft, this inspection must be performed within 12 calendar months after the last inspection and must include checking for:
1. PROPER INSTALLATION: Verification that the ELT is securely mounted in accordance with the manufacturer’s instructions and FAA guidance. Proper installation minimizes the probability of damage in a crash and ensures optimal signal transmission.8
2. BATTERY CORROSION: A thorough visual inspection for any signs of corrosion on the battery terminals or surrounding areas.9 Corrosion can significantly degrade battery performance and even lead to complete failure.10
3. OPERATION OF CONTROLS AND CRASH SENSOR: Testing the manual activation switch and verifying that the internal crash sensor (if applicable) is functional.11 For 406 MHz ELTs, this often involves following the manufacturer’s specific test procedures.
4. SUFFICIENT SIGNAL RADIATED FROM ITS ANTENNA: This is perhaps the most crucial part of the ELT inspection. It involves testing the ELT’s ability to transmit a clear and strong signal from its antenna. For 121.5 MHz ELTs, this is typically a three-audible-sweep test performed during the first 5 minutes after any hour, or coordinated with ATC if performed outside this window.12 For 406 MHz ELTs, specific self-test procedures outlined in the manufacturer’s instructions are followed, often involving a momentary test transmission that can be detected by the Cospas-Sarsat system to confirm functionality without triggering a false alert.13
THE AERO CENTER ADVANTAGE: CONSISTENCY AND EXPERTISE
Maintaining your ELT in peak condition requires a consistent approach to maintenance, something The Aero Center excels at. Our team of experienced aviation mechanics understands the intricacies of ELT systems and is dedicated to ensuring every unit we service meets or exceeds FAA regulations. We apply a rigorous checklist to every ELT inspection and battery replacement, guaranteeing nothing is overlooked.
Many pilots and aircraft owners in California, Arizona, and Nevada have entrusted their aircraft to us, relying on our proven track record of thoroughness and adherence to the highest safety standards. This social proof speaks volumes about the quality of our work. When it comes to something as vital as an ELT, you want the authority in aviation maintenance, and that’s precisely what The Aero Center offers. We utilize the latest diagnostic tools and adhere strictly to manufacturer specifications and FAA Advisory Circulars, such as AC 91-44A, which provides detailed guidance on ELT operational and maintenance practices.
Furthermore, we understand that aircraft downtime can be costly. That’s why The Aero Center proudly offers 24/7 maintenance services, a unique selling proposition in our region. This commitment means we can perform your ELT battery replacements and inspections efficiently, often outside of traditional business hours, minimizing the impact on your flying schedule.
Your ELT is a silent guardian, waiting to be called upon in an emergency. Don’t compromise on its readiness. Adhering to FAA regulations for battery replacement and testing is a non-negotiable aspect of responsible aircraft ownership.
FOOTNOTES
- Federal Aviation Administration. 14 CFR Part 91, Section 91.207 – Emergency locator transmitters. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C/part-91/section-91.207
- Federal Aviation Administration. Advisory Circular 91-44A – Operational and Maintenance Practices for Emergency Locator Transmitters and Receivers. https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_91-44A.pdf
- AOPA. Emergency Locator Transmitters ELTs. https://www.aopa.org/advocacy/aircraft/aircraft-operations/emergency-locator-transmitters
The Aero Center is located at William J. Fox Airfield KWJF | Lancaster, CA. Contact us at 209.885.6950 for questions or appointments.