The FAA has requested that Boeing supply more evidence to prove that electrical faults found in its 737 MAX cockpits don’t extend into other parts of the aircraft, slowing down the repair of dozens of jets.
The 106 Boeing 737 MAX jets affected by recently reported electrical faults may remain grounded for longer than first anticipated, as air safety officials continue to request more information from the US planemaker.
Industry sources said Boeing has been requested to supply additional analysis and documentation to prove that additional 737 MAX subsystems are not impacted by similar electrical grounding faults to those that have been found in three areas of the aircraft’s cockpit, according to Reuters.
According to anonymous industry sources, Boeing submitted a service bulletin to the FAA late last week that advises airlines on how to rectify the grounding safety issues that have been identified to date.
While the FAA initially approved the service bulletins, after discussions with Boeing, the regulator asked for additional information and analysis on whether or not any other subsystems throughout the jet could be affected by similar grounding issues.
The FAA intends to then review Boeing’s analysis and make any necessary revisions to the service bulletins before they can be sent to airlines.
The new requirements are likely to mean that an imminent ungrounding of the 106 affected MAX aircraft will be delayed.
US airlines earlier said that they are expecting information on a solution to the electrical issues within the next week, however this timeline is likely to be affected by this latest push for further information from Boeing.
Electrical flaws were initially found in a number of MAX cockpits’ backup power control systems in mid-April.
The electrical issue involves a lapse in the grounding capabilities of some electrical circuits located in the cockpit. Grounding capabilities are vital in order to maintain a user’s safety in the event of a surge of voltage that could otherwise result in a shock or electrocution.
The issue was labelled by Boeing as being caused by a “production issue”, and was limited to jets delivered in the months after the Federal Aviation Administration lifted its grounding ban on the MAX.
However, the FAA later stated that “subsequent analysis and testing showed the issue could involve additional systems”, including the standby power control unit, a circuit breaker panel and main instrument panel.
Now nearly a quarter of all delivered MAX jets are affected by and FAA airworthiness directive keeping them on the ground until Boeing finds a way to rectify the issue.
In its service bulletin, Boeing has proposed adding a bonding strap or cable that workers screw onto two different surfaces creating a grounding path, for the affected electrical circuit, two of the sources said.
The sources also specified that the electrical grounding problems that have been located to date came as a result of Boeing changing a manufacturing method, as it worked to increase the speed at which it can produce the jet.
They said that the change made, which sparked the issues, pertained to a hole-drilling process.
Boeing initially told airlines that rectifying the issue could take as little as a few hours, or up to a few days, per jet.
“We continue to work closely with the FAA and our customers to address the ground path issue in affected 737s,” a Boeing spokeswoman said.