BA Boeing Co

By Andy Pasztor and Andrew Tangel 

Potentially hazardous wiring inside Boeing Co.'s 737 MAX jets is the latest flashpoint between U.S. and European regulators and a further complication in the grounded fleet's return to service, according to people familiar with the details.

Technical experts at the European Union Aviation Safety Agency want certain electrical wires relocated to reduce what they say are dangers from potential short circuits, which in a worst-case scenario could disrupt flight-control systems, according to these people.

In addition to the Federal Aviation Administration's ongoing safety review of proposed fixes to the MAX, the European agency is independently vetting such changes.

But engineers at the Chicago plane maker and high-ranking FAA managers, including the agency's top safety official, contend moving the wiring isn't necessary, one of these people said. Boeing hasn't yet submitted its formal recommendation, though the issue is headed for a decision in the next few weeks by FAA head Steve Dickson.

The disagreement over whether to take action on the wiring, which hasn't been reported before, has prompted the FAA to hold off scheduling a key certification flight for the MAX. It also highlights the emergence of a series of new technical challenges and delays confronting the Chicago plane maker as it strives to get the MAX back in the air world-wide. The planes have been grounded since last March, following two fatal crashes that killed 346 people.

The planes are expected to gradually start resuming commercial flights sometime in the summer, with major U.S. carriers having removed them from schedules until June.

On Saturday, the FAA released a statement saying Boeing recently informed the agency "about concerns associated with the location of wiring in certain areas of the MAX." Since then, according to the statement, "the FAA has closely monitored the company's analysis and how the issue might affect the ongoing certification efforts." The wiring concerns were reported earlier by the New York Times.

Reiterating earlier statements, the FAA said the MAX will be approved to carry passengers again "only after our safety experts are fully satisfied that all safety-related issues are addressed."

A Boeing spokesman said the company is cooperating with international regulators on a thorough certification process, "and we are working to perform the appropriate analysis." He said, "It would be premature to speculate as to whether this analysis will lead to any design changes."

A spokeswoman for EASA, which also hasn't submitted its final position to the FAA, declined to comment. The issues still could be resolved with a compromise, but Boeing's priority at this point, according to some of the people familiar with the details, is avoiding any wire modifications.

The wires, which help control movable panels on the tail and power other systems, may be too close to each other in a dozen locations from the rear of the aircraft to the main electronics compartment beneath the cabin and behind the cockpit, according to the people familiar with the issue.

A short circuit, or "arcing" of electrical current between wires, could cause control problems for pilots that the FAA characterizes as hazardous or in some cases even catastrophic, according one of the people briefed on the details.

EASA and FAA technical experts, along with some other FAA officials responsible for certifying aircraft designs, have taken the position that safety rules require wiring modifications in such instances, this person said.

The relevant international rules relate to safety enhancements put in place more than a decade ago after an in-flight fire caused a Swissair jet to plunge into the water near Nova Scotia in 1998, killing all on board.

The current concerns about potential wiring problems stem from Boeing's analysis of how short circuits could cause problems with some flight-control systems, and how quickly pilots could react to those emergencies.

Since the two fatal crashes, safety regulators have been reassessing certain MAX flight-control systems, changing software, adjusting related computers and modifying pilot training.

Last month, industry and government officials revealed the latest software glitch, a problem that prevents the jet's flight-control computers from powering up and verifying they are ready for flight, and said Boeing was working to resolve it.

Addressing the wiring issues would pose tough logistical and financial hurdles. How the agency mandates fixes may depend on who owns the aircraft, according to another person familiar with the details. The FAA may require Boeing to fix wiring on approximately 400 undelivered aircraft now in storage at airfields dotting the Puget Sound area, this person said.

For planes previously delivered to carriers, the agency would likely perform a risk analysis to determine whether the wiring should be repaired either before the planes fly again or during routinely scheduled maintenance, this person added.

Relocating the wiring bundles would take roughly two weeks per plane, according to industry and government experts. Such fixes could be performed at the same time as software and training updates, depending on available manpower, to try to minimize additional delays.

Write to Andy Pasztor at andy.pasztor@wsj.com and Andrew Tangel at Andrew.Tangel@wsj.com

(END) Dow Jones Newswires

February 01, 2020 23:11 ET (04:11 GMT)

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