What is the maximum differential pressure allowed up to 37,000 ft?

What is the maximum differential pressure allowed up to 37,000 ft?

• A. 6.5 psi
• B. 7.8 psi
• C. 8.4 psi
• D. 8.8 psi

Answer: (B)

Differential pressure is the difference between cabin pressure and outside air pressure, and it’s limited by the aircraft’s structure and pressurization system to keep the fuselage safe under flight loads. For the ERJ 175, that certification limit up to 37,000 ft is 7.8 psi. That means the cabin can be pressurized such that the pressure difference does not exceed 7.8 psi at those altitudes, ensuring the fuselage isn’t stressed beyond what it’s designed to handle. The system maintains this through pressure control and relief mechanisms, so if the differential nears the limit, it will be managed to avoid surpassing it. Options higher than 7.8 psi would push beyond the certified structural limit at that altitude, while a lower value would still be allowable but not the maximum. Hence 7.8 psi is the correct maximum.

Differential pressure is the difference between cabin pressure and outside air pressure, and it’s limited by the aircraft’s structure and pressurization system to keep the fuselage safe under flight loads. For the ERJ 175, that certification limit up to 37,000 ft is 7.8 psi. That means the cabin can be pressurized such that the pressure difference does not exceed 7.8 psi at those altitudes, ensuring the fuselage isn’t stressed beyond what it’s designed to handle. The system maintains this through pressure control and relief mechanisms, so if the differential nears the limit, it will be managed to avoid surpassing it. Options higher than 7.8 psi would push beyond the certified structural limit at that altitude, while a lower value would still be allowable but not the maximum. Hence 7.8 psi is the correct maximum.