What might indicate an overpressure event in the aircraft oxygen system on transport category aircraft?

An indication of an overpressure event in the aircraft oxygen system is often associated with the condition of the pressure gauge reflecting elevated pressure levels. When the pressure gauge reads zero, it generally suggests that there is no pressure in the system, which could potentially be a result of a catastrophic failure or a significant leak rather than an overpressure condition.

In contrast, the missing green thermal expansion disk is specifically designed to relieve pressure in cases of overpressure and would typically provide a visual indicator of a possible issue if it is absent. The reference to inconsistent oxygen flow points to potential blockage or other operational issues, whereas the depletion of the oxygen supply relates to the exhaustion of the available oxygen, not directly to overpressure. The correct response centers on the pressure gauge’s reading, which is critical in diagnosing the state of the oxygen system and understanding if it is functioning within safe pressure parameters.