During taxi, takeoff, and landing, the pressure differential must not exceed which value?

• A. 0.1 PSI
• B. 0.5 PSI
• C. 0.2 PSI
• D. 0.3 PSI

Answer: (A)

Pressure differential is the difference between the cabin pressure and the outside air pressure. During taxi, takeoff, and landing, the aircraft is near the ground and structural loading from high differential pressures must be avoided to protect doors, seals, and the fuselage while systems are transitioning or not fully in cruise mode. Keeping the differential very small, at 0.1 psi, provides a conservative margin so a fault or unexpected pressurization change won’t create undue loads on the aircraft structure or door mechanisms during these phases. The other values would allow larger differentials and could increase stress on the fuselage, seals, or door operation when the airplane is on the ground or near it.