What is the maximum cabin differential pressure allowed?

• A. 9.5 psi
• B. 10.3 psi
• C. 10.0 psi
• D. 11.0 psi

Answer: (B)

Differential pressure is the difference between the air pressure inside the cabin and the pressure outside the aircraft. The fuselage is built to withstand a specific maximum difference, and the pressurization system is designed to hold the cabin at or below that limit to protect structural integrity and ensure safe operation at altitude. For this airplane, the published maximum cabin differential pressure is 10.3 psi, so the system will regulate to keep the cabin pressure such that the difference does not exceed that value. That’s why 10.3 psi is the best answer—it reflects the official design limit for this airframe. Exceeding this limit could stress the fuselage or lead to unsafe conditions, while the other values are either below the certified maximum or exceed it.