TSO is good for how many days?

• A. 90 days
• B. 180 days
• C. 270 days
• D. 360 days

Answer: (B)

How long a TSO remains in effect before renewal is the concept being tested. The correct duration is 180 days. This six-month window provides a practical balance: it gives enough time to use the authorization for planned work, arrange any required maintenance or inspections, and still prompts timely review so nothing sits out of date. Shorter periods, like 90 days, would cause frequent renewals and disrupt workflow, while longer periods, such as 270 or 360 days, could allow conditions to change without updated oversight. If more time is needed, there’s typically a process to extend or renew the TSO before it expires to maintain control and accountability.