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I upgraded my sim to P3D v4.4. My MJC Dash 8 version is v1.020a.
I don't hear any engine sound or PA sound inside the flight deck. In external view, sound is ok.
Provided that you have updated the aircraft using the patch accessible via the User Area, you should not be experiencing this issue. We have not gotten any reports of this nature with the recent P3D v4.4 update either.
You may also want to check you sound devices to ensure that they are properly set if not using a 5.1 sound system.
I had this same problem after reinstalling the Q400 on my new flight sim pc. After much head scratching and contemplating a full reinstallation of FSX:SE & the Q400 I noticed that when my head was turned towards the FO (I use TrackIR) I caught some of the pushback instructions. After investigation it appears that Windows 10 had set my speakers to 5.1 even though I had told it I was only using 2 channel speakers. All is now working as it should. Check your sound setup in Windows...