After a spectacular mid-flight incident last week, United and Alaska Airlines both revealed on Monday that early checks had found unsecured hardware on some of their Boeing 737 MAX 9 aircraft.
The revelations coincide with the investigation being conducted by US federal transportation inspectors into the cause of an Alaska Airlines passenger plane’s “door plug component blowing out” last Friday, which resulted in an emergency landing.
United reported that it has “found instances that appear to relate to installation issues in the door plug — for example, bolts that needed additional tightening.”
Hours later, Alaska Airlines said its staff had found that “loose hardware was visible on some aircraft.”
As investors started to evaluate the incident’s financial effects, Boeing shares fell sharply on Monday. Meanwhile, US aviation regulators gave airlines procedures to inspect aircraft that resembled the Friday’s incident’s 737 MAX 9.
Inspectors from the National Transportation Safety Board (NTSB) said late on Monday that while they had not yet established if the bolts for the component that broke off on Friday’s Alaska Airlines aircraft either existed or flew off with the panel, they had not found any.
Through further equipment testing, “we will be able to determine whether the bolts were there,” NTSB Chair Jennifer Homendy told reporters.
Homendy said the investigation was concentrated on Friday’s event, but he refrained from directly addressing the most recent revelations from Alaska and United regarding loose components. However, she added, if necessary, the board might make an urgent safety recommendation.
A portion of the MAX fleet was grounded, which resulted in the cancellation of hundreds of flights.
