The Boeing Company
Coupling Nut Visible Tightness Indicator

Abstract:

In an example, a fitting assembly configured to visibly indicate nut tightness when coupling a first component to a second component is disclosed. The fitting assembly comprises a nut comprising a threaded portion and a chamber portion, wherein the chamber portion comprises one or more through-holes. The fitting assembly also comprises an indicator slidably disposed within the chamber portion, a retainer assembly disposed within the chamber portion and configured to interlock with an inner surface of the nut, and a spring disposed within the chamber portion between, and engaging, the indicator and the retainer assembly. The retainer assembly is configured to interface with the spring to retain the spring within the chamber portion. The fitting assembly is configured to receive the first component and the second component such that, when the nut is rotated, a visibility of the indicator through the one or more through-holes changes.