Upper coupler assemblies (10) for mounting coupling devices (14) to trailers (12), and methods for inspecting upper coupler assemblies (10). The assemblies (10) include a housing (16) having first and second members (18,20) that define a cavity (22) therebetween. At least the second member (20) has a through-hole (24) adapted to receive a coupling device, such as a kingpin (14). The cavity (22) contains at least one fluid-tight chamber (30A-30E,32A-32D), more preferably multiple gas-tight and liquid-tight chambers (30A-30D,32A-32D) separated by walls (34) within the cavity (22). The assembly (10) has at least one fluid inlet (38,44) for introducing and/or withdrawing a fluid (liquid and/or gas) from one or more of the chambers (30A-30E,32A-32D). The integrity of the upper coupler assembly (10) can be evaluated by introducing or removing a gas from chambers (30A-30E,32A-32D) and detecting the presence of gas leaks in chambers (30A-30E,32A-32D).