If I remember correctly, there was some sort of issue with the F-16 on the earlier point releases of P3D v4. I don't remember which, but one of the point releases ended up fixing the spoiler issue. You may wish to review the release notes for each newer version of v4 to see where it was noted.
If you're not up to date, I'd consider updating your client and content for P3Dv4 to a more recent release.
Aerosoft F-16 Spoiler not working
in Prepar3D
Posted
If I remember correctly, there was some sort of issue with the F-16 on the earlier point releases of P3D v4. I don't remember which, but one of the point releases ended up fixing the spoiler issue. You may wish to review the release notes for each newer version of v4 to see where it was noted.
If you're not up to date, I'd consider updating your client and content for P3Dv4 to a more recent release.