FAA AMT (Aviation Maintenance Technician) Airframe Practice Exam

What component of a pressurization system prevents the cabin altitude from becoming higher than airplane altitude?

1. Positive pressure relief valve

2. Negative pressure relief valve

3. Outflow valve

4. Cabin pressure regulator

The correct answer is: Negative pressure relief valve

The correct answer is the negative pressure relief valve because its main function is to prevent the cabin altitude from becoming higher than the airplane altitude. If the cabin altitude were to exceed the airplane altitude, it could lead to structural damage due to excessive pressure differential. This valve allows excessive cabin pressure to escape, ensuring that the cabin altitude does not surpass the airplane altitude. Option A, the positive pressure relief valve, is responsible for preventing the cabin pressure from exceeding its maximum allowable limit by releasing excess air within the cabin. Option C, the outflow valve, controls the outflow of air from the pressurized cabin to maintain the desired cabin altitude. Option D, the cabin pressure regulator, is in charge of regulating and maintaining the desired cabin pressure during different flight phases.