Re: There's a thought....
After the loss of MH370, there's serious moves to have blackbox data live egressed off airliners back to some appropriate secure data centre. This has been possible for a long time (Inmarsat offer a suitable service AFAIK), but because it costs money no / few airlines had taken it up. The loss of MH370 has probably caused a bit of a re-think amongst aviation regulators.
However, this is not much of an option for light aircraft / small helicopters.
There's quite a lot of data you can extract from the sound recording. If the engine noise is audible (which it is on a helicopter, small aircraft, even quite large airliners) you can judge power settings, RPM, etc. reasonably well. The sound of the air rushing past can give a crude indication of airspeed, and whether or not there was rain / hail hitting the windscreen. All useful information in the absence of anything else.