A logo of Airbus is seen at the entrance of the Jean-Luc Lagardere A380 production plant at Airbus headquarters in Blagnac, near Toulouse, France June 18, 2020.
A logo of Airbus is seen at the entrance of the Jean-Luc Lagardere A380 production plant at Airbus headquarters in Blagnac, near Toulouse, France June 18, 2020. Reuters / Stephane Mahe

Airbus faces a months-long delay in the development of its A321XLR jet, pushing its arrival to 2024, as European regulators consider imposing changes to a lower-fuselage design to contain potential fire risks, industry sources said on Wednesday.

The latest upgrade to the planemaker's best-selling A321 single-aisle jet had been due to enter service in late 2023, but that timetable has been delayed by discussions with regulators about certification of a new rear-central fuel tank.

The European Union Aviation Safety Agency (EASA) is looking at imposing significant changes to the design of the "underbelly fairings," part of the plane's lower structure, two of the sources said.

The curved composite structure would have to be redesigned in heavier metal and also extended in length, they said.

Such work could add 6-9 months of work depending on the scope of the final certification rule, one of the sources said.

A second source said this and other work on temperature management could add as much as a year to the timetable, though Airbus is seen as unlikely to adopt such a worst-case scenario immediately.

Airbus and EASA confirmed they were in talks on how to certify the new long-range narrowbody model without elaborating.

"The certification of the A321XLR is an ongoing project," an EASA spokesperson said.

"The complete set of conditions in relation (to) the installation of the rear-centre tanks is still under definition, and, when ready, will be published for comments."

An Airbus spokesperson said, "As the discussions with the airworthiness authorities are still ongoing, we are not in a position to comment."

Rival Boeing has expressed concerns about fire risks from the new A321XLR design.

The certification talks surround the question of whether extra protections to the plane's underbelly are needed in the event of a crash.

An industry source told Reuters last March that a prolonged debate over the design could push the aircraft's entry to service to 2024.

Bloomberg News reported earlier that any design changes could also shorten the Airbus plane's range, a key battleground in its battle with Boeing in the busiest part of the market.

The Airbus spokesperson said the planemaker expects "no significant impact" on range.

Airbus is due to publish quarterly results on Wednesday evening when it routinely updates investors on development plans as well as progress towards proposals to raise jet production.

Engine makers said last week they had agreed new production plans for 2024, indicating a possible rise in planned output.