A Boeing 737 MAX sits outside the hangar during a media visit to the Boeing plant in Renton, Washington.
Matt Mills McKnight | Reuters
An electrical problem that led to dozens of Boeing 737 Max’s suspended from service worsened after engineers found similar grounding faults elsewhere in the cockpit, industry sources said on Friday.
Airlines decommissioned dozens of Max jets a week ago after Boeing warned of a production-related electrical grounding issue in an emergency power control unit located in the cockpit of some recently built aircraft.
Since then, suspected grounding issues have been discovered at two other locations in the cockpit, the sources said.
These include the storage medium where the relevant control unit is kept and the dashboard facing the pilots.
Boeing made no immediate comment on the larger issue, namely first reported by Aviation Week.
Boeing shares closed down 1.2%.
The issue – which affects about a fifth of Max jets on the market – is the latest issue to plague Boeing’s best-selling model, but is unrelated to design issues that contributed to a global safety ban 20 months following two fatal accidents. .
Boeing should write bulletins telling airlines how to troubleshoot grounding issues or electrical paths designed to maintain safety in the event of a power surge.
US regulators must first approve the bulletins.
While most analysts believe the fix should be relatively straightforward, no details were immediately available on the timing of the repair bulletins needed to begin work on some 90 jets affected by the suspension.
The aircraft maker initially told airlines that a fix could take hours or days by plane, according to a notification seen by Reuters when the partial suspension was first announced.
The issue was attributed to a change in material coating after production of the 737 Max resumed last year.
Almost all of the affected jets were built before Max deliveries resumed in December, shortly after U.S. regulators lifted the fleet-wide ban caused by the 2018 and 2019 crashes.
Boeing said it plans to gradually increase production of the 737 Max from a current unspecified “low rate” to a target of 31 jets per month by early 2022. Industry sources believe it is currently producing about four jets per month.
Air sources say Boeing has not delivered any Max planes, however, since the electrical problem was identified last week.