About the loud thump heard in the CVR, the following is from the transcript of the Alaska Air crash due to tail plane jackscrew integrity.
1619:36.6 CAM [sound of extremely loud noise] [increase in background noise begins and continues to end of recording] [sound similar to loose articles moving around in cockpit]=left
1619:37 CAM-? *=left
1619:37.6 PA [sound similar to CVR startup tone]=left
1619:43 CAM-2 mayday.=left
1619:49 CAM-1 push and roll, push and roll.=left
1619:54 CAM-1 ok, we are inverted... and now we gotta get it….=left
1619:59 CAM [sound of chime]=left
1620:03 CAM-1 kick *=left
1620:04 CAM-1 push push push... push the blue side up.=left
1620:14 CAM-1 push.=left
1620:14 CAM-2 I'm pushing.=left
1620:16 CAM-1 ok now lets kick rudder... left rudder left rudder.=left
1620:18 CAM-2 I can't reach it.=left
1620:20 CAM-1 ok right rudder... right rudder.=left
1620:25 CAM-1 are we flyin?... we're flyin... we're flyin... tell 'em what we're doin.=left
1620:33 CAM-2 oh yea let me get *=left
1620:35 CAM-1 *=left
1620:38 CAM-1 gotta get it over again... at least upside down we're flyin.=left
1620:40.6 PA [sound similar to CVR startup tone]=left
1620:42 CAM-? *=left
1620:44 CAM-? *=left
1620:49 CAM [sounds similar to compressor stalls begin and continue to end of recording]=left
1620:49 CAM [sound similar to engine spool down]=left
1620:54 CAM-1 speedbrakes.=left
1620:55.1 CAM-2 got it.=left
1620:56.2 CAM-1 ah here we go.=left
1620:57.1 [end of recording]