Abstract: The present disclosure discloses an arm mechanism (100) for docking an unmanned aerial vehicle (200), to a structure for conducting non-destructive testing. The arm mechanism (100) comprises a bracket (101), which is connected to a body (201) of the unmanned aerial vehicle (200). Further, the arm mechanism (100) comprises a pair of members (M) positioned in the bracket (101), and each of the pair of members (M) are configured to rotate relative to movement of a driving unit (D). Furthermore, the arm mechanism (100) comprises at least one arm (104), which is coupled to each of the pair of members (M). Actuation of the driving unit (D), drives each of the pair of members (M) to angularly displace each of the at least one arm (104), to facilitate adjustment of arms (104) for docking the unmanned aerial vehicle (200) to different geometrical structures for conducting non-destructive testing.