Which statement correctly describes irregular supersession?

• A. Based on a specific, pre-determined date
• B. Regular supersession
• C. Not pre-determined, but occurs as a result of use
• D. Emergency supersession

Answer: (C)

Irregular supersession is when replacement isn’t tied to a fixed calendar date. Instead, the item is substituted based on its condition or how much it has been used. You monitor wear, fatigue, or performance indicators, and once the item no longer meets standards or is deemed no longer safe or effective, it’s replaced. This keeps equipment ready and reliable without sticking to a strict schedule.

This differs from regular supersession, which happens on a pre-set timetable, and from emergency supersession, which is triggered by an immediate failure or hazard. For example, a tool or component might be replaced after wear is observed during inspection, even though the calendar date hasn’t arrived yet.