Originally Posted by
Oldlae
Unless an aircraft is already wired up with the required sensors and possible instruments it would be quite a task to install a FDR but not impossible. However, a CVR or a Video Camera trained on the Instrument panel would suffice for an interim period. Back in the day, and I have been retired too long to know about modern technology, the CVR's on BHL aircraft had four channels one of which read the Rotor RPM, which might have been useful in the pub accident investigation.
Modern EFIS aircraft with everything on a digital data bus should be much easier than in times of old. Yes you still need a DFDAU to package all the data together into the right format/frame rate, but such things as air data, attitude and heading, control positions, engine and system parameters will most likely already exist in digital format so probably no additional sensors required, and the above data will probably already be on just a few ARINC429 busses, even if not already concentrated onto 1 general purpose bus to eg feed the screens.