Complex sentence: RA-Aus reported that it was supplied with only a fraction of CASA's source data--just a day before submissions closed--and that CASA seemed to have excluded all engine reliability data post- "early 2014".
Split into simpler sentences: RA-Aus reports that they were supplied only a fraction of CASA's source data just 1 day before submissions closed. And that CASA seems to have excluded all engine reliability data post "early 2014".