The preliminary report “should be regarded as tentative”, a spokesperson for the authority said on Thursday.
The AAIA also made a recommendation to the European Union Aviation Safety Agency (EASA) to require Rolls-Royce to “develop continuing airworthiness information, including but not limited to, inspection requirements of the secondary fuel manifold hoses” of the engines in question.
Cathay’s incident prompted other airlines in Asia to carry out similar checks on their A350-900 and A350-1000 models, which are powered by Rolls-Royce Trent XWB-84 and XWB-97 engines, respectively.
The European Union Aviation Safety Agency also mandated inspections on A350-1000s.
There are 86 such planes in service worldwide, according to the EASA.
Qatar Airways is the biggest operator of the 1000 version, with 24 in its fleet, followed by Cathay Pacific and British Airways, which both operate 18.
Airbus and Rolls-Royce earlier said they are cooperating with Cathay, but could not comment further pending the investigation.
