Resettable overpressure indicator for aircraft

A passive pressure or overpressure indicator apparatus for use in a compartment of an aircraft engine nacelle, the indicator apparatus comprising:

• a housing configured for attachment within the interior of the compartment of the aircraft engine nacelle;
• a pressure sensing element disposed within the housing, the pressure sensing element having access to the exterior of the compartment via at least one venting passage disposed within the housing in order to detect a pressure differential between the interior and exterior of the compartment wherein the venting passage is configured to meter ambient air to the pressure sensing element;
• an indicator element movably coupled to the pressure sensing element between a nominal position and a triggered position, in which a distal end of the indicator element is caused to move exterior of the compartment in the triggered position to provide a visual indication when a predetermined pressure differential between the interior and the exterior of the compartment indicative of an overpressure condition is detected by the pressure sensing element;
• and
• a reset mechanism for resetting the indicator element to the nominal position, the reset mechanism including at least one reset feature that can only be accessed by opening the compartment of the aircraft engine nacelle.