Batteries need to be replaced when the ELT has been used more than one cumulative hour or 50 percent of the useful charge or life has expired.
Reference(s):
14 CFR 91.207 Emergency locator transmitters
Practical Review for the Checkride
Batteries need to be replaced when the ELT has been used more than one cumulative hour or 50 percent of the useful charge or life has expired.
Reference(s):
14 CFR 91.207 Emergency locator transmitters