Several airlines around the globe have temporarily grounded their B737 MAX jets after Boeing identified “a potential electrical issue” in a specific group of the aircraft. The US manufacturer said in a statement on 9 April that it had recommended to 16 unspecified operators that they verify that their B737 MAX have a sufficient ground path for a component of the electrical power system.

“We are working closely with the US Federal Aviation Administration on this production issue,” it said. “We are also informing our customers of specific tail numbers affected and we will provide direction on appropriate corrective actions.”

Sources familiar with developments told Reuters that around 90 MAX around the world are affected. David Seymour, CCO of American Airlines, told staff in an internal memo seen by the news agency that Boeing had traced the issue to a production change made in the installation process.

“[It] occurred after our last aircraft was delivered before the fleet grounding in March 2019,” he said, adding that the issue affected 17 of AA’s most recently delivered B737 MAX.

Southwest Airlines said 30 of its 58 MAX were affected, while United Airlines removed 16 of its 30 MAX from operation. Alaska Airlines has grounded all four of its B737-9s. In Europe, Blue Air has grounded its recently delivered B737-8, reported, as a precaution even though Boeing has yet to notify it on whether its jet is among those affected.