^^^The black boxes, as in CVR and FDR, have acoustic pingers for underwater search, but not a radio beacon. An ELT is generally not mounted near them.
Anyone know what g force is required to set an applicable ELT off? Had a quick search but no actual figure found.
For current generation 406 MHz beacons, the activation threshold is 2.3 +/- 0.3 G, with a change in velocity (delta V) of 4.5 +/- 0.5 ft/sec (1.4 m/sec +10%). There is also an impulse curve (acceleration vs time) which must be complied with.
For the US, the requirements are contained in FAA TSO C-126b, "406 MHz Emergency Locator Transmitter, (ELT)" which references for specific requirements, document RTCA/DO-204A "Minimum Operational Performance Standards for 406 MHz Emergency Locator Transmitters (ELT)."
Per RTCA, DO-204A is harmonized with EUROCAE ED-62, "Minimum Operational Performance Specification for Aircraft Emergency Locator Transmitters on 406 MHz AND 121.5 MHz (Optional 243 MHz)" The above numbers were taken directly from DO-204A and ED-62.
Regarding carriage of ELTs, the Cospas-Sarsat program, referenced earlier, publishes document C/S S.007 "Handbook of Beacon Regulations" which "...provides a summary of regulations issued by Cospas-Sarsat Participants regarding the carriage of 406 MHz beacons. It also includes practical information on coding and registration requirements in each country, where such information was made available to the Cospas-Sarsat Secretariat."
http://www.cospas-sarsat.org/images/...7_sept2013.pdf