Perhaps only additional circumstantial evidence but AA020 DFW>LHR on 7/15 delayed nearly two hours and required a plane swap due to an A/C maintenance issue according to the notes on EF. Surprisingly, the notes didn’t indicate the new metal but I watched the original bird sit at D23 unmoving while pax were moved to a different plane at D27. Should’ve checked the tail numbers before and after the announcement, I suppose, but considered myself lucky there was another 772 hanging around with the right load package or the delay may have been much longer.