Abstract: A decompression panel assembly (12) for use in an aircraft separation structure (14). The panel assembly includes a support pan (26) having an opening (28), a bull nose (64) extending outwardly from the support pan at the opening's edge, and a recess (62) surrounding the bull nose. An inner seal (70) is sized and located within the recess (62). A retaining ring (22) is provided and includes a number of fingers (84) formed from spaced-apart slits (86) extending into the retaining ring (22) from the ring's inner edge. The assembly (12) further includes a pressure relief panel (24) shaped similar to the support pan opening shape, though sized slightly larger. The pressure relief panel (24) is held between the support pan bull nose (64) and the retaining ring (22) during non-decompression use. A number of index pins (94) interconnect between the retaining ring and the support pan. A grill (30) is attached to the support pan to protect the pressure relief panel.