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Boeing 737 Max: debris found in fuel tanks of grounded planes

Boeing has ordered inspections of its entire fleet of grounded 737 Max planes after it found debris in the fuel tanks of some of the aircraft, in the latest setback for the US planemaker.

The specialist aviation blog Leeham News, which first reported the discovery of the “foreign object debris” (FOD), said the inspections would likely not delay the recertification of the jets. However, it will take up to three days to inspect each plane because fuel must be drained and vapours dissipated before the fuel tanks can be opened.

Mark Jenks, the general manager of the 737 programme, said in a memo to employees that the debris was “absolutely unacceptable” and that the company was taking steps to address the problem in its production system.

Timeline

Boeing’s 737 Max crisis

Boeing's new advice

Boeing issues revised instructions on how pilots should react to erroneous readings from “angle of attack” sensors, believed to be a key factor in the Lion Air crash.

Ethiopia Airlines crash

Flight ET302 crashes about six minutes after taking off from the Ethiopian capital, Addis Ababa, killing all 157 people onboard. The captain had reported difficulties, and flight radar data shows the aircraft was climbing erratically with an unstable vertical airspeed.

Boeing grounds fleet

The EU, Canada and the US all ground the Boeing 737 Max. Boeing itself issues a statement saying it “continues to have full confidence in the safety of the 737 Max”, but that “out of an abundance of caution and in order to reassure the flying public” it w recommending the grounding of the entire global fleet of 371 aircraft.

Interim report findings

The interim report into the Ethiopian Airlines crash finds that the pilots correctly followed Boeing’s emergency instructions, but were still unable to stop the plane’s nose repeatedly pointing down. The jet hit an airspeed of 500 knots (575mph), well above its operational limits, before cockpit data recordings stopped.

A new potential risk

Airlines extend their ban on using the Boeing 737 Max after the US aviation regulator said it had identified a new potential risk with the plane.

Airbus soars

In the wake of Boeing’s troubles, Airbus seems set to overtake it as the world's biggest planemaker. As Boeing reported 239 commercial plane deliveries in the first half of the year, a 37% fall, rival Airbus shipped 389 deliveries, up 28% on the same period last year.

Sensor concerns ignored

During congressional hearings into Boeing’s handling of the crisis, lawmakers were shown internal records revealing that three years before the crashes an employee had expressed concern that an anti-stall flight system could be triggered by a single sensor.

The crisis deepens with the release of hundreds of internal messages between employees working on the 737 Max aircraft, which boasted of deceiving safety regulators and said the plane had been “designed by clowns”.

Boeing orders inspections of its entire fleet of grounded 737 Max planes after it found foreign object debris in the fuel tanks of some of the mothballed planes.

“During these challenging times, our customers and the flying public are counting on us to do our best work each and every day,” Jenks said, adding: “One escape is one too many.”

It is less than a year since the second fatal crash of a Boeing 737 Max resulted in the grounding of the model’s entire global fleet and the company is racing to recertify with regulators that the planes can fly safely.

The fuel tank problem is unrelated to the flaws to sensors thought to have contributed towards the two crashes.

Boeing built about 400 of the planes, which it could not deliver to customers, and its orders have suffered after it was forced to cut back production at its factory near Seattle.

Foreign object debris, an industrial term for rags, tools, metal shavings and other materials left behind by workers during the production process, has been a quality control issue for various Boeing aircraft, such as its KC-46 tankers. Material left in planes during assembly can raise the risk of electrical short-circuiting and fires.

The objects were found during maintenance work on some of the hundreds of 737 Max jetliners Boeing has built but not delivered because of the global ban on the 737 imposed last March.

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A Boeing official said the debris was discovered in several planes but did not give a precise number.

The spokesman said the problem would not change the company’s belief that the Federal Aviation Administration would certify the plane to fly again this summer.

An FAA spokesman said the agency knows that Boeing is conducting a voluntary inspection of undelivered Max planes. He said the FAA “increased its surveillance based on initial inspection reports and will take further action based on the findings”.