It is, kind of. The plug is secured by 6 stops (or tabs) along each side. The positive pressure differential pushes the plug outwards into those stops.

To remove the plug you uninstall 4 bolts which allow the plug to go up and over the stops, after which it can hinge outwards on a hinge found at the bottom of the plug.

Source: https://youtu.be/WhfK9jlZK1o?si=dbUV1i2nNFcNixQh

[–] EeeDawg101@lemm.ee 1 points 10 months ago

Just seems like a better design would be if no bolts existed (like from them loosening over time and falling off), it would still be sealed perfectly fine. The obvious failure point is the bolts and seems they could do better.