Two safety valves in the aft bulkhead serve to ___?

• A. Protect against over pressurization and negative pressure.
• B. Regulate cabin temperature.
• C. Block fuel venting during high altitude.
• D. Drain condensate from packs.

Answer: (A)

These two safety valves are part of the pressurization protection system. Their role is to vent cabin air automatically if pressure rises above safe limits or drops below safe levels, preventing structural damage and passenger discomfort from a pressure excursion. In normal operation the cabin pressure controller and the outflow valve regulate pressure, and the safety valves stay closed until a fault or abnormal condition pushes the pressure outside the safe range. They’re located in the aft bulkhead to provide reliable overboard venting. The other listed functions—temperature regulation, blocking fuel venting, or draining condensate—are handled by different systems and components, not these valves.