Air safety officials in the United States have asked Boeing Co to supply fresh analysis and documentation showing that numerous subsystems in its 737 MAX planes would not be affected by electrical grounding issues first flagged in three areas of the jet in April, two people familiar with the matter have told the Reuters news agency.
The extra analysis injects new uncertainty over the timing of when Boeing’s best-selling plane would be cleared to fly by the US Federal Aviation Administration (FAA) reported Reuters on Tuesday.
The electrical problems have suspended nearly a quarter of its 737 MAX fleet.
US airlines have said they had expected Boeing to release service bulletins as soon as this week that would have allowed them to make fixes and soon return the planes to service, but this latest issue will likely push that timeline back.