Several airlines around the globe have temporarily grounded their B737 MAX jets after Boeing (BOE, Chicago O'Hare) identified "a potential electrical issue" in a specific group of the aircraft.

In a statement on April 9, the US manufacturer said 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, chief operating officer of American Airlines (AA, Dallas/Fort Worth), 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 (WN, Dallas Love Field) said 30 of its 58 MAX were affected, while United Airlines (UA, Chicago O'Hare) removed 16 of its 30 MAX from operation. Alaska Airlines (AS, Seattle Tacoma Int'l) has grounded all four of its B737-9s. In Europe, Blue Air (Romania) (0B, Bucharest Otopeni) has grounded its recently delivered B737-8, Boardingpass.ro reported, as a precaution even though Boeing has yet to notify it on whether its jet is among those affected.

The B737 MAX has only just made a return to commercial service after it was grounded in March 2019 following the crashes of two B737 MAX 8s that killed a total of 346 people.