PARIS (Reuters), – European aviation regulators may make significant design changes to the “underbelly fairings,” which will be used on the A321XLR’s future Airbus A321XLR. This would increase the likelihood of delays in the introduction of the aircraft, according to a senior source within the industry.

This move was made to reduce the possibility of a fire from a central fuel tank. Bloomberg News had reported that design changes could also shorten the plane’s range.

Airbus spokesmen said that they were in negotiations with European Union Aviation Safety Agency, (EASA), about the certification requirements. EASA could not be reached immediately for comment.