The rules in both total warfare and the battlemech manual state that when a mech shuts down the unit needs to make a PSR at a +3 to avoid falling. It later states that a player can voluntarily shutdown, making a distinction between forced shutdowns and manual shutdowns.
Does the unit have to make a PSR if the shutdown is voluntary in nature? The way the rules are written, it doesn't make a distinction between the 2 for purposes of the PSR and doesn't explicitly state that voluntary shutdown s do not require a PSR.....