II / SAS
I very much doubt that the 1022 hz tone was relevant. That frequency corresponds to a rotational speed of 61,320 rpm or for say a gear with 30 teeth, gear meshing frequency at 2044 rpm which I think is much faster than the upper epicyclic planets are going. It is more likely to be an avionics cooling fan or even electrical (not sound) interference picked up on the microphone leads.
Interesting but one could spend one's life chasing sounds that are not related to the transmission.