A top cap assembly is provided for mounting tendon to a balloon that has a balloon envelope. The assembly includes a plate structure having a plurality of junction portions disposed at an apex of the balloon envelope and a plurality of tendon pairs. Each tendon pair includes first and second tendon members attached to the balloon envelope. The first tendon member is arranged to cross over the plate structure. The second tendon member is arranged to engage the first length tendon member at a given one of the junction portions of the doubler plate. A fastener member is attached to each tendon pair of the plurality of tendon pairs. The fastener member is used for securing the first and second tendon members of a given tendon pair together in order to support lift gas carried by the balloon envelope.