Probe finds Cathay Airbus defect could cause 'extensive' damage

An engine defect in the Airbus A350 plane that led to the cancellation of dozens of Cathay Pacific flights in early September could have escalated into "extensive damage", according to the results of a Hong Kong probe released Thursday.

Hong Kong-based Cathay briefly grounded its fleet of A350s for inspections and repairs after a Zurich-bound plane was forced to turn around and head back to the Chinese city on September 2.

The inspections found that components on 15 of the 48 planes in the fleet of A350s, powered by engines from the British manufacturer Rolls-Royce, had to be replaced.

In Thursday's report, the Hong Kong investigators said a post-flight examination of the Zurich-bound plane found that a fuel hose had ruptured, as evidenced by a "discernible hole", burn marks and "black soot observed on the aft section of the core engine".

The fuel could have leaked through the ruptured hose and resulted in a fire that would have spread to surrounding areas, said the report released by the Air Accident Investigation Authority (AAIA).

"If not promptly detected and addressed, this situation... could escalate into a more serious engine fire, potentially causing extensive damage to the aircraft," it said, categorising the incident as "serious".

Five additional fuel hoses in the Zurich-bound plane -- which was manufactured in 2019 -- were also found to have either "frayed metal braids or collapsed structures", the authority said.

To address the issue, the AAIA recommended that the European Union Aviation Safety Agency 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.

Thursday's preliminary report "should be regarded as tentative", a spokesman said.

The Cathay 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.

The European Union Aviation Safety Agency also mandated inspections on A350-1000s as a "precautionary measure", noting that there are 86 such aircraft in service worldwide.

However, it said mandatory inspections of Airbus A350-900 engines were "not warranted at this stage".

Qatar Airways is the biggest operator of the A350-1000, with 24 in its fleet, followed by Cathay Pacific and British Airways, which both have 18.

Airbus and Rolls-Royce earlier said they were cooperating with Cathay, but could not comment further pending the investigation.

Last November, Emirates chief executive Tim Clark expressed concerns about the durability and longevity of A350 engines.

Rolls-Royce has defended its Trent XWB-97 engines and said it is taking steps to improve their durability.