Lobed nut cap

A cap for forming a sealed cavity around an end of a fastener, the cap comprising a cap body having a collar portion terminating at a rim which surrounds an opening for receiving the end of the fastener, the collar portion having three or more discrete contact regions distributed around an internal face thereof, each contact region being arranged to contact the end of the fastener when the collar portion is installed on the end of the fastener, wherein the collar portion has a lobed shape in cross-section such that a radially outwardly bulging lobe extends between each neighbouring pair of contact regions, the cap having an annular flange which extends radially outwardly from the collar portion at an intersection which is set back from the rim so as to define an annular sealing cavity between the flange and the collar portion.

A cap for forming a sealed cavity around an end of a fastener, the cap comprising a cap body having a collar portion terminating at a rim which surrounds an opening for receiving the end of the fastener, the collar portion having three or more discrete contact regions distributed around an internal face thereof, each contact region being arranged to contact the end of the fastener when the collar portion is installed on the end of the fastener, wherein the collar portion has a lobed shape in cross-section such that a radially outwardly bulging lobe extends between each neighbouring pair of contact regions, the cap having an outer cap member arranged to be installed over the cap body so as to enclose the cap body, the outer cap member having an annular collar portion and an annular flange which extends radially outwardly away from the annular collar portion, the annular flange and annular collar portion between them defining an annular sealing cavity for receiving sealing material.

A joint comprising:

• a structure;
• a fastener passing through the structure so that an end thereof protrudes from the structure, wherein the fastener comprises a nut;
• and a cap providing a sealed cavity around the end of the fastener, the cap comprising a cap body having a collar portion terminating at a rim which surrounds an opening for receiving the end of the fastener, the collar portion having three or more discrete contact regions distributed around an internal face thereof, each contact region contacting the end of the fastener, wherein the collar portion has a lobed shape in cross-section such that a radially outwardly bulging lobe extends between each neighbouring pair of contact regions, and wherein a sealant material provides a seal between the collar portion of the cap and the structure.