The US Federal Aviation Administration (FAA) has ordered Boeing to make repairs on a number of its 737 MAX jets that are currently grounded due to an electrical problem.
In an airworthiness directive published on Wednesday, the agency issued specific instructions on how to fix the problem.
According to the FAA, a total of 106 planes from the 737-8 and 737-9 series are affected, 71 of which are licensed in the US. The repairs should require an estimated maximum of 24 hours of work per aircraft.
Some three weeks ago, the FAA had received a report of an electrical bonding and grounding issue that was discovered during testing of a newly manufactured Boeing 737-8.
During standard production testing by Boeing, electrical power systems did not perform as expected. Investigations identified insufficient bonding of certain metallic support panel assemblies installed in two areas of the flight deck.
US airlines voluntarily withdrew dozens of planes from service.
The airworthiness directive indicates that rectifying the problem may not be too expensive. The FAA put the cost of repairing the 71 aircraft registered in the US at around 155,000 dollars.
In addition to the jets in operation, hundreds of 737 MAX aircraft which Boeing has built since 2019 and not yet handed over to customers will also need to be repaired.
Boeing 737 MAX jets have only returned to service recently. They were banned from flying for around 20 months after two crashes with a total of 346 deaths. The aircraft was only recertified in the US in November.