What is the maximum cabin differential in cruise?

• A. 4.50 PSID
• B. 5.75 PSID
• C. 6.00 PSID
• D. 6.50 PSID

Answer: (B)

Cabin differential pressure is how much higher the air inside the cabin is compared with the air outside. In cruise, the pressurization system keeps this difference within a safe limit to protect the fuselage from structural loads. For the PC-12 NGX, that maximum positive differential is 5.75 PSI. That means the cabin pressure must never exceed outside pressure by more than 5.75 PSI; the system will vent air to hold a safe differential if needed. This limit is set by certification and structural design, ensuring safe operation across the flight envelope. The other values fall short of the true maximum or exceed what the airframe is certified to withstand, so 5.75 PSI is the correct limit.