The profoundly toxic Honeywell Aerospace site lists the Digital Flight Data Acquisition Unit used in the Boeing 777.
http://www.honeywell.com/sites/aero/...74EACA8348.htm To read the specification sheet, you need to register for a Honeywell ID. This will take several days to get.
The Honeywell unit is a 12 bit A/D with a single 12 bit sample per second for fuel and engine parameters.
A sub-harmonic that is 7 octaves below the fundamental is quite unlikely to be resolved with a 12 bit A/D and a single sample.
A better bet might be to analyze the audio track of any amateur video shot of the landing.
If anyone has a pointer to these, post it here and I can take a look at the audio track.