What describes the differential pressure range?

• A. The operating range that extends from where the isobaric range stops
• B. The isobaric range stops and outside altitude increases
• C. The cabin altitude equals outside altitude
• D. The bleed air temperature is reduced

Answer: (A)

Differential pressure range is the span of pressure difference the pressurization system can safely regulate across the cabin. During flight, there’s an isobaric range where cabin pressure is held constant as altitude changes. Once that isobaric range ends, the system operates within the differential pressure range, allowing the cabin pressure to differ from outside pressure up to the system’s maximum allowable ΔP. So the differential pressure range is best described as the operating range that begins where the isobaric range stops and extends to the maximum differential pressure the structure and system can safely withstand. The other statements don’t define this range: zero differential (cabin pressure equals outside) isn’t it, and bleed air temperature is unrelated to differential pressure.