  We introduce a new invariant of a cubic graph - its regular defect - which is
defined as the smallest number of edges left uncovered by any collection of
three perfect matchings that have no edge in common. This invariant is a
modification of defect, an invariant introduced by Steffen (J. Graph Theory 78
(2015), 195--206), whose definition does not require the empty intersection
condition. In this paper we discuss the relationship of this invariant to the
well-known conjectures of Fulkerson (1971) and Fan and Raspaud (1994) and prove
that defect and regular defect can be arbitrarily far apart.
