Private Pilot Private Exam

When are non-rechargeable batteries of an emergency locator transmitter (ELT) required to be replaced?

1. When 50 percent of their useful life expires

2. Every month

3. When the battery indicator shows low

4. After 1 year of use

The correct answer is: When 50 percent of their useful life expires

The requirement for replacing non-rechargeable batteries in an emergency locator transmitter (ELT) hinges on the lifespan of the battery. When 50 percent of their useful life expires, it indicates that the battery has reached a critical point where it may no longer function reliably in an emergency situation. This precaution helps ensure that the ELT can transmit a distress signal effectively when needed, which is crucial for search and rescue operations. Setting the replacement criterion at the halfway point allows sufficient time to replace the batteries without risking their malfunction while still within their designated life period. This practice promotes safety and readiness, as ELTs play a vital role in locating downed aircraft. Other options do not provide adequate guidelines for battery management. Monthly checks could be impractical given typical battery life spans, while relying solely on a low battery indicator does not guarantee timely replacement. Replacing batteries after one year, without regard to their condition or usage, could lead to situations where the battery has reached its end of life before being replaced. Thus, the method of replacing batteries after 50 percent of useful life aligns best with safety requirements.