write:Another mishap type involves aircraft with mul-tiple unvented pressurized compartments. Imagine an aircraft with two or more separate pressur-ized compartments. If one compartment

does not consider upstream failures such as misrigging and locking hook stall which will allow the lock’s ac-tuator to move but not detect the failure of the locking mechanism’s moving into the proper position. This concept obviously has application to all warning systems. Whenever a failure of a warning system is in-volved in a mishap
the investigator needs to ask the question
“Exactly what was the warning system warning of?”Other accidental openings (e.g. fatigue fail-ure of the skin
failures of windows
penetrations made by failed engine components) made in the hull of a pressurized airplane have resulted in crew or passengers being ejected at altitude.Another mishap type involves aircraft with mul-tiple unvented pressurized compartments. Imagine an aircraft with two or more separate
pressur-ized compartments. If one compartment is de-pressurized
the other will maintain its pres-sure. If
in addition
the structure between the two compartments can-not withstand the load created by the resulting differential pressure
the structure between the two compartments will fail if one side is depres-surized. Critical com-ponents located in the structure separating the two pressure vessels
can be destroyed and loss of the entire aircraft is pos-sible. Figures 35-6
35-7
Figure 35-5. Door Lock Warning System Design (Misrigged; “False” Locked Indication)Figure 35-6. Structure Separating Pressurized Compartments and Containing Critical Equipment.Figure 35-7. Loss of Pressure in One Compartment.