StratOps 175, Repair and Replacement, subsection Destroyed vs. Truly Destroyed, explains Aerospace units, WarShips, DropShips, etc, all irrecoverably destroyed when SI reduced to 0. Salvageable components may remain.
Complete Destruction states that if any unit is destroyed due to ammo explosion, no salvageable components remain.
Paragraph at the bottom of page 175, same section, same subsection contains aerospace specific information.