Before opening the cabin door after turning off the vent blower, how long must the vent blower be off?

Before opening the cabin door after turning off the vent blower, how long must the vent blower be off?

• A. 15 seconds
• B. 60 seconds
• C. 90 seconds
• D. 45 seconds

Answer: (D)

Ventilation systems can still contain residual air in the ducts after you switch off the vent blower. Giving a short wait lets that air purge and the cabin pressure settle, so when you open the door there isn’t a sudden gust or pressure difference pushing air or objects around. The 45-second pause is the specified purge/equalization time for this aircraft, ensuring a smooth, safe door operation. Shorter times might leave residual air, and longer times don’t provide added safety benefits.

Ventilation systems can still contain residual air in the ducts after you switch off the vent blower. Giving a short wait lets that air purge and the cabin pressure settle, so when you open the door there isn’t a sudden gust or pressure difference pushing air or objects around. The 45-second pause is the specified purge/equalization time for this aircraft, ensuring a smooth, safe door operation. Shorter times might leave residual air, and longer times don’t provide added safety benefits.