What is the normal differential pressure?

What is the normal differential pressure?

• A. 9.8
• B. 10.2
• C. 10.5
• D. 10.0

Answer: (B)

Normal differential pressure is the difference between cabin pressure and outside air during normal cruise operation. It’s typically about 5 psi, which keeps the cabin comfortable while staying within the airframe’s structural limits. That 5 psi translates to roughly 10.2 inches of mercury, because 1 psi is about 2.036 inHg; 5 psi ≈ 10.18 inHg. So 10.2 inHg is the standard value used for the normal differential pressure. The other options correspond to nearby values rounded differently but do not match the commonly cited normal figure.

Normal differential pressure is the difference between cabin pressure and outside air during normal cruise operation. It’s typically about 5 psi, which keeps the cabin comfortable while staying within the airframe’s structural limits. That 5 psi translates to roughly 10.2 inches of mercury, because 1 psi is about 2.036 inHg; 5 psi ≈ 10.18 inHg. So 10.2 inHg is the standard value used for the normal differential pressure. The other options correspond to nearby values rounded differently but do not match the commonly cited normal figure.