(New York) Boeing shares opened sharply lower on Monday, following the incident that saw a door come loose on an Alaska Airlines flight on Friday, while the investigation continues into shed light on this dysfunction.

In early trading on Wall Street, the airline manufacturer’s price dropped 8.38%. That of its main subcontractor, Spirit AeroSystems, even declined sharply (-13.74%).

This is a new setback for the aircraft manufacturer, whose stock had recovered since the beginning of autumn, with the acceleration of its deliveries, long disrupted by technical problems.

The door of the 737 MAX 9 aircraft of the American company Alaska Airlines, torn from the cabin in mid-flight on Friday, was found on Sunday, announced the president of the American transport safety agency (NTSB), Jennifer Homendy.

A teacher recovered the sign, which had fallen in his garden in the city of Portland (Northwest Oregon). “We are going to go get it and start analyzing it,” said the head of the National Transportation Safety Board during a press conference.

On Sunday, Boeing CEO Dave Calhoun decided to cancel a conference that was to bring together the group’s senior executives at the start of the week, replacing it with a safety meeting on Tuesday, open to all employees.

It will be held at the Renton (Washington State) factory, a suburb of Seattle.

NTSB, Boeing, Alaska Airlines and the American civil aviation regulatory agency, the FAA, are seeking to establish the exact circumstances of the incident, which caused only a few minor injuries, but could have ended “in more tragic way,” according to Jennifer Homendy.

The flying door was blocked on the incriminated plane, a configuration that Boeing offers to its customers when the number of existing emergency exits is already sufficient in relation to the number of seats in the aircraft.

In addition to the 737 MAX 9, this device already exists on other Boeing models, notably the 737-900er, launched in 2006 and which has not experienced any similar incidents since.

According to the NTSB, no one was seated in the two seats next to the partition that flew away. But according to passengers cited by American media, a teenager sitting in the row had his shirt torn off by the decompression, causing him minor injuries.

After this very rare malfunction, the FAA “required immediate inspections of certain Boeing 737 MAX 9s before they can resume flight”, which concerns 171 aircraft worldwide, she said on X.

As a result, airlines and safety agencies around the world have grounded some Boeing 737 MAX 9s pending inspections.

Keeping these aircraft on the ground has already led to the cancellation of more than a thousand flights since Saturday, according to data from the specialized site FlightAware, mainly for Alaska Airlines and United, which operate 144 of the 218 MAX-9s in circulation.

On Monday, Alaska Airlines was also penalized on Wall Street, dropping 5.56%.

The companies Aeromexico, Copa Airlines, which operates 21 of these aircraft, and Turkish Airlines, which owns 5, also announced that they had grounded their planes for checks.

On the other hand, the European Aviation Safety Agency (EASA) indicated that no operator in Europe uses the 737 MAX 9 with the technical options concerned.

The incident marks a new episode in a series of setbacks for Boeing in recent years.

The most serious of these were the crashes of two 737 MAXs, in October 2018 in Indonesia and March 2019 in Ethiopia, which caused the deaths of a total of 346 people.

After these accidents, linked to the MCAS piloting software, all 737 MAXs were grounded for 20 months.

But the American manufacturer has also suspended, on several occasions, for almost two years in total, deliveries of its long-haul 787 for manufacturing and inspection defects.

More recently, it was once again the 737 MAX that made headlines, after the discovery, in the fall, of faulty workmanship on the rear watertight bulkhead of the aircraft, then in December, of a risk of a loose bolt. on the rudder control system.

By the end of December, the manufacturer had delivered more than 1,370 copies of the 737 MAX and its order book exceeded 4,000 units.