The Federal Aviation Administration (FAA) proposed another safety fix to the Boeing 737 MAX before it can return to service.

The proposed airworthiness directive (AD) follows a report that a manufacturing defect on certain exterior panels of the 737 MAX could make it vulnerable to a lightning strike, potentially leading to dual-engine power loss. The defect was discovered in December 2019.

The proposed AD, which was posted Tuesday on the Federal Register’s website, would require a detailed inspection of a metallic lining that serves as a shield against lightning strikes or high intensity radiated fields (HIRF) on Boeing’s model 737-8 and 737-9 jets. It would also require replacement of any excessively reworked panels and some thorough modification.

RELATED: Exclusive: Boeing CEO talks relationship with FAA in recertification of 737 MAX

A Boeing spokesperson said the protective foil inside the composite panels may have gaps on some jets built between February 2018 and June 2019.

The FAA must receive any comments on the proposed AD by March 27.

Earlier this month, Boeing said that it found debris contaminating the fuel tanks of some 737 MAX jets that it built in the past year but was unable to deliver to airline customers.

RELATED: Boeing finds a new issue with 737 MAX, debris in fuel tanks

The fuel tank debris was discovered during maintenance on parked planes, and Boeing said it immediately made corrections in its production system to prevent a recurrence. Those steps include more inspections before fuel tanks are sealed.

Approximately 800 737 MAX jets have been grounded since last March after two deadly crashes killed 346 people. The grounding is expected to be lifted sometime in 2020, but a specific date has not been announced.

The Associated Press contributed to this report.