U.S. regulators are ordering airlines to fix a manufacturing flaw on electrical components on Boeing Co. 737 Max jets that had idled more than 100 of the planes around to world.

Repairs to address the “unsafe condition” will cost about $155,000 to fix the 71 planes in operation in the U.S., the Federal Aviation Administration said Wednesday in a notice. Airlines voluntarily grounded the planes while awaiting guidance from Boeing.

Bonding that is essential to grounding electrical components could have caused engine anti-ice protection and other functions to fail, the FAA said in what is known as an airworthiness directive, providing new details about the problem.

“The FAA is issuing this AD to prevent loss of critical functions and/or multiple simultaneous flight deck effects, which may prevent continued safe flight and landing,” the agency said in the directive, which it posted to a government website in advance of it appearing in the Federal Register on Friday.

In addition to the planes in service needing the repairs, there are several hundred jets built since 2019 and currently in storage that will also have to be fixed. Most nations are expected to follow the FAA’s lead and adopt the directive for their carriers.

“We fully support the FAA’s directive to address electrical issues identified in certain locations in the flight deck of select 737 Max airplanes,” Boeing said in an emailed statement.

The company has been working with FAA engineers to finalize a bulletin detailing how to make the repairs, the company said. The FAA plans to order that the work follows Boeing’s instructions.

The work should take about 24 hours per plane for the 68 aircraft on which multiple electrical panels require repairs, the FAA said. The remaining three planes will need about nine hours each.

The FAA is waiving the normal period to accept public comment to speed enactment of the directive. The FAA order was earlier reported by Reuters.