text: can anyone help me with this aircraft oxygen system question i had on a jar aircraft engineering test? during a demonstration of the operation of a passenger chemical oxygen generator the panel was manually opened and the masks deployed. the lanyard was pulled but no oxygen flowed from the hose to the face masks? can anyone diagnose possible faults in this scenario?? thanks manual deployment of the masks di not arm the oxygen generator, so they did not actuate and thus no oxygen flow. the pulling of the oxygen mask lanyard only frees the connection of that particular mask to the header, not the actuation of the o2 generator.