The SAIB is focused on ELTs from ACR Electronics, Inc. (ACR, formerly Artex Aircraft Supplies, Inc., and Chelton Avionics, Inc.), models G406-4, C406-1, C406-1HM, C406-2, C406-2HM, C406-N and C406-NHM. According to the agency, these ELTs may not transmit alert and location signals in the case of an accident involving an aircraft to which they are mounted due to an inoperative or a deteriorated G-switch. The SAIB states that an ELT mounted in a high-vibration environment, for example in the tail of a helicopter, could have its acceleration sensor deteriorate after having been subjected to high levels of shock and vibration for five years or more. The new SAIB recommends best practices for the inspection, modification and replacement of these ACR ELTs located in high-vibration environments. In our view, these recommendations can be applied to similar ELTs from other vendors.