US regulators are demanding a rewire of the Boeing 737 Max before certification is granted, having rejected Boeing’s proposal to leave wiring bundles in place on the grounded 737 Max.

In January, Boeing and the FAA announced a review of a wiring issue which could potentially cause a short circuit on the 737 Max. Under certain circumstances this could cause the plane to crash if pilots did not react in time.

Wiring bundles found to be too close together

Wiring bundles have been found to be too close together on a number of different locations within the 737 Max, with most being under the cockpit. If wiring bundles are seen to pose a potential hazard, regulators would require separation of the bundles or adding a physical barrier.

The FAA said yesterday that it “continues to engage with Boeing as the company works to address a recently discovered wiring issue with the 737 Max.” It added that: “The manufacturer must demonstrate compliance with all certification standards.”

FAA states bundles do not meet safety standards

Boeing had told the Federal Aviation Administration (FAA) that it does not believe it needs to separate or move wiring bundles on its grounded 737 Max jetliner. But according to Reuters, a source had said the FAA told Boeing on Friday that it did not agree with the manufacturer that the wiring bundles met safety standards.

Boeing said on Sunday it was in ongoing discussions with the FAA over the issue, although a US official said it was “unlikely” the FAA would reconsider.

Boeing’s entire 737 Max fleet was grounded last March following two crashes in Indonesia and Ethiopia which killed 346 people.