[vhfpmr (OP)]

This seems to suggest that they only record control inputs but not the outputs, is that correct? If so, it seems to me that whilst you know if the pilots actions were at fault, you can only infer whether the control surfaces comply with the pilots controls from the behaviour of the plane, and not directly from recorded data.

[SeanB]

Modern ones record a lot more, but manufacturer specific, so there might be control surface feedback, but that really is not needed, as the recorder will also record the flight computer error logs, which does have that, and the flight computers also have a simpler form of data logger, which often does survive, as it is in a ruggedised casing. Engine FADEC also has the same, which is on the engine itself, and in many crashes the engine separates off the pylon, and thus this data recorder is readable to some extent, as it often is not involved in a fire.

But the engine cutoff switches could have a fault cause them to show as turned off, though it is hard to imagine, as each runs in a cable bundle to the engine FADEC, though there is a common section and connectors they run through, which could be the actual fault, the cable either being damaged, or the plug not being properly locked, and coming intermittent or falling loose. entirely possible, as the plugs are locked with a 3 pin bayonet latch, and it is possible to mate the plug and have electrical connection without the latching taking place, and the plug vibrating loose till it falls out.

[vhfpmr (OP)]

the plug not being properly locked, and coming intermittent or falling loose. entirely possible, as the plugs are locked with a 3 pin bayonet latch, and it is possible to mate the plug and have electrical connection without the latching taking place, and the plug vibrating loose till it falls out.

Engines Off: 08:08:41, 08:08:42
Engine 1 On: 08:08:52
Engine 2 On: 08:08:56

It's not simultaneous enough for a plug falling out, even less falling out and back in again.

[Bored chemist]

I gather the flight data recorders record position.
That is the essential output of the control signals from the pilot(s).
If the pilot flying pulls up, but the aircraft does not, that tells you quite a lot.

[alancalverd]

The FDR will also record airspeed and angle of attack, so will clearly record the precursor to a stall if you pull up with inadequate thrust, which seems to be the case with the Air India crash.

[Petrochemicals]

I should think they have been updated over the years, I would think that video is possible. But it is all worthless lf they cannot be recovered as in the case of mh370 or the 2024 crash Korea where they recorded nothing due to the loss of power.