Are you just talking about the screws that hold the panels to the engine, e.g. such as the part seen opened here? If so, aircraft engines that have panels attached by screws instead of latches typically have many screws holding them on, and there are regulations as to how many can be missing. Depending upon the panel, a single one missing probably would not be an issue. There was probably an entry in the maintenance chart noting it and to have it replaced when next due.


BTW, missing screws, open and exposed sensitive areas, coincidence?!